As auto repair professionals, understanding EOBD/OBDII live data is vital for effective diagnostics and repair. CARDIAGTECH.NET offers expert guidance and top-quality tools to help you interpret real-time vehicle data, pinpoint issues, and optimize performance. Grasping the nuances of EOBD/OBDII live data unlocks precision diagnostics and efficient repairs, offering a competitive edge in the automotive service industry. Discover diagnostic insights that lead to precise solutions!
1. Understanding EOBD/OBDII Live Data Fundamentals
Electronic On-Board Diagnostics (EOBD) and On-Board Diagnostics II (OBDII) are standardized systems in modern vehicles that monitor engine performance and emissions. Live data, also known as real-time data, refers to the continuous stream of information from various sensors and systems within the vehicle. This data is crucial for diagnosing issues, verifying repairs, and understanding how different components are functioning.
1.1. The Importance of Real-Time Vehicle Data
Real-time vehicle data is essential for several reasons:
- Accurate Diagnostics: Live data helps pinpoint the root cause of problems by showing how systems behave under different conditions.
- Efficient Repairs: By analyzing real-time information, technicians can avoid unnecessary repairs and focus on the actual problem areas.
- Performance Monitoring: Live data allows you to monitor the engine and other systems’ performance, ensuring optimal efficiency and preventing potential issues.
- Verification of Repairs: After completing a repair, live data can confirm that the problem has been resolved and that the system is functioning correctly.
1.2. Navigating the EOBD/OBDII System
EOBD and OBDII systems use a standardized set of diagnostic trouble codes (DTCs) and data parameters. The systems monitor various components, including the engine, transmission, fuel system, and emissions control system. Understanding how to access and interpret this data is crucial for any auto repair professional.
2. Key EOBD/OBDII Live Data Parameters
Several key parameters provide critical insights into a vehicle’s health and performance. Here’s a breakdown of some of the most important ones:
2.1. Engine-Related Parameters
2.1.1. Engine RPM (Revolutions Per Minute)
Engine RPM indicates how fast the engine’s crankshaft is rotating. Monitoring RPM is crucial for diagnosing issues related to engine speed, idle control, and overall performance. High RPMs when the engine is idle or fluctuating RPMs can indicate problems with the idle air control valve, vacuum leaks, or other engine issues.
2.1.2. Vehicle Speed
Vehicle speed measures how fast the vehicle is moving. This parameter is essential for diagnosing issues with the transmission, ABS, and other speed-related systems. Discrepancies between the indicated speed and actual speed can point to sensor malfunctions or transmission problems.
2.1.3. Engine Coolant Temperature
Engine coolant temperature measures the temperature of the engine coolant. This is vital for monitoring engine operating temperature and diagnosing cooling system issues. Overheating or failure to reach optimal temperature can indicate problems with the thermostat, radiator, or coolant sensors.
2.1.4. Engine Oil Temperature
Engine oil temperature is measured using thermocouples, thermistors, or RTD sensors and is crucial due to its specific working range. Monitoring the oil temperature ensures that the engine is properly lubricated and cooled. High oil temperatures can lead to decreased engine life and potential damage.
2.1.5. Ambient Air Temperature
Ambient air temperature, measured by a thermometric sensor, affects engine performance. This data helps the engine control unit (ECU) adjust fuel trim and timing based on the external environment.
2.1.6. Barometric Pressure
Barometric pressure, measured by the BARO sensor, affects fuel trim and engine timing. The PCM uses this information to adjust the engine’s operation based on altitude and weather conditions.
- Note: The average vehicle barometric pressure is 14.7 PSI at sea level.
2.1.7. Accelerator Pedal Position
Accelerator pedal position measures how far the accelerator pedal is depressed. This is critical for diagnosing issues with throttle control and engine response. Inconsistent or erratic readings can indicate problems with the pedal position sensor or throttle actuator.
2.1.8. Relative Accelerator Pedal Position
Relative accelerator pedal position evaluates the accelerator pedal position based on the output voltages to the pedal position. This reading may not always show 100% when the pedal is fully depressed due to sensor variations.
- Note: The sensor may display the average value of multiple position sensors depending on the vehicle.
2.1.9. Commanded Throttle Actuator
The commanded throttle actuator position represents the throttle position requested by the ECM based on accelerator pedal position. It indicates the desired throttle opening, which is compared to the actual throttle position to ensure proper engine response.
2.1.10. Relative Throttle Position
Relative throttle position compares the throttle position and the learned closed position. Adjustments are made to compensate for changes in throttle behavior due to carbon buildup or other factors.
2.1.11. Absolute Throttle Position
Absolute throttle position measures the actual opening of the throttle, ranging from 0% (completely closed) to 100% (fully open). Monitoring this parameter ensures the throttle is responding correctly to the driver’s input and the ECM’s commands.
2.1.12. Control Module Voltage
Control module voltage measures the voltage supplied to the engine control unit. Proper voltage is essential for the ECM to function correctly. Low or unstable voltage can cause various performance issues and diagnostic trouble codes.
- Note: This is not the same as the battery voltage.
2.1.13. Hybrid Battery Pack Remaining Life
Hybrid battery pack remaining life indicates the total charge percentage in the hybrid battery pack. This parameter is crucial for assessing the health and performance of hybrid vehicles.
- Note: Standard OBD2 doesn’t show individual cell data.
2.1.14. Hybrid/EV Vehicle System Status
Hybrid/EV vehicle system status provides information on the operation of hybrid and electric vehicle systems, including charging state, battery voltage, and current.
- HEV Charging State: Charge Sustaining Mode (CSM) or Charge Depletion Mode (CDM).
- HEV Battery Voltage: Ranges from 0V to 1024V.
- HEV Battery Current: Ranges from -3300 Amps to 3300 Amps (negative value indicates charging state).
2.1.15. Calculated Engine Load Value
Calculated engine load value is derived from the MAF sensor value and represents the current airflow in the engine relative to the peak airflow. This parameter is used to assess engine efficiency and performance under different load conditions.
- Note: Altitude corrects peak airflow.
2.1.16. Absolute Load Value
Absolute load value is the normalized percentage value of air mass per intake stroke, calculated by dividing air mass per intake stroke by air mass per intake stroke at 100% throttle.
- Note: Values differ when your vehicle is idle, parking, or without accessories.
2.1.17. Driver’s Demand Engine – Percent Torque
Driver’s demand engine percent torque represents the maximum available engine torque based on accelerator pedal position, cruise control, and transmission requests. This parameter reflects the driver’s input and the ECM’s response.
- Note: External factors such as traction control and ABS won’t affect the values.
2.1.18. Actual Engine – Percent Torque
Actual engine percent torque, also known as indicated torque, shows the current percentage of total available engine torque, net brake torque, and friction torque required to run the engine without load.
2.1.19. Engine Friction – Percent Torque
Engine friction percent torque represents the maximum engine torque percentage required to run a fully equipped no-load engine, including internal engine components, fuel, water pump, air intake, alternator, exhaust, and emission control equipment.
2.1.20. Engine Reference Torque
Engine reference torque is a torque rating of the engine considered as 100% value for actual engine percentage torque and other parameters with percentage torque outputs.
- Note: Its value is constant and never changes over time.
2.1.21. Engine Percent Torque Data
Engine percent torque data is used when changes in vehicle conditions can cause torque reference to change. This parameter allows the ECM to adjust torque calculations based on various operating conditions.
2.1.22. Auxiliary Input/Output
Auxiliary input/output provides details of various vehicle system statuses:
- On or Off Status of Power Take Off and Glow Plug Lamp
- Park/Neutral or Drive/Reverse Status of Automatic Transmission
- Neutral/Clutch In or In Gear Status of Manual Transmission
- 1 to 15 Status of Recommended Transmission Gear
2.1.23. Exhaust Gas Temperature (EGT)
Exhaust gas temperature (EGT) is measured by sensors installed on the following systems to protect components from overheating:
- Turbo Charger
- Catalytic Converter
- Diesel Particulate Filter
- Components of the NOX reduction system
2.1.24. Engine Exhaust Flow Rate
Engine exhaust flow rate is the flow rate of the air and fuel mixture ignited using a spark plug. It is calculated using exhaust temperature, volumetric efficiency, engine size, and flywheel RPM.
2.1.25. Exhaust Pressure
Exhaust pressure is displayed as an absolute pressure value when the engine is on and roughly ambient atmospheric value when it is off.
- Note: Report data from one or two exhausts depends on vehicle configuration.
2.1.26. Manifold Surface Temperature
Manifold surface temperature measures the temperature of the exhaust manifold’s outer surface. This parameter helps monitor the thermal conditions of the exhaust system.
2.1.27. Timing Advance for #1 Cylinder
Timing advance for #1 cylinder is a manufacturer-specific timing regarding the angle of the top dead center (TDC) and the time before the #1 cylinder should fire.
- Note: A positive value means delayed spark plug firing, and a negative value means spark plug fires before #1 cylinder reaches the top.
2.1.28. Engine Run Time
Engine run time measures the total run time of the following engine statuses:
- Engine Run Time in Seconds
- Engine Idle Time In Seconds
- Engine Run Time when PTO is engaged
2.1.29. Run Time Since Engine Start
Run time since engine start measures the total run time in seconds since the engine starts ignition.
2.1.30. Time Run with MIL On
Time run with MIL on measures the total engine run time since the activation of the check engine light after a code is thrown.
- Note: This parameter is different from total elapsed time.
2.1.31. Distance Traveled while MIL is Activated
Distance traveled while MIL is activated measures the total distance your vehicle has traveled since the check engine light activation.
- Note: This parameter will reset once codes are cleared, or your vehicle’s battery is disconnected.
2.1.32. Time since Trouble Codes Cleared
Time since trouble codes cleared measures the total engine run time since the codes were cleared by your OBD2 Scan tool or the battery is disconnected.
2.1.33. Distance Traveled Since Codes Cleared
Distance traveled since codes cleared measures the total distance covered by the vehicle since the codes were cleared by the OBD2 Scan tool or battery is disconnected.
- Note: This parameter will not reset even if clearing non-engine codes are done.
2.1.34. Warm-ups Since Codes Cleared
Warm-ups since codes cleared measures the total number of engine warm-up cycles after clearing codes or disconnecting the battery.
- Note: A warm-up cycle is achieved when the coolant temperature reaches at least 40 °F after startup and reaches at least 170 °F.
2.2. Fuel & Air-Related Parameters
2.2.1. Fuel System Status
Fuel system status indicates the status of two fuel systems, which run in Open and Closed Loop Mode.
- Open Loop Modes: The engine computer uses pre-programmed air: fuel ratios to decide the amount of fuel to be injected.
- Closed Loop Mode: The ECM uses the O2 sensor feedback to adjust the air: fuel ratio to prevent too much air or gas condition.
2.2.2. Oxygen Sensor Voltage
Oxygen sensor voltage measures the generated O2 voltage within the vehicle system, typically ranging from 0.1 V to 0.9 V. Monitoring this voltage ensures that the O2 sensor is functioning correctly.
2.2.3. Oxygen Sensor Equivalence Ratio
Oxygen sensor equivalence ratio, also known as the Lambda sensor, informs the engine to adjust the fuel and air mixture in closed loop mode. In open loop mode, the engine does not use this feedback.
2.2.4. Oxygen Sensor Current
Oxygen sensor current indicates the current that flows within the Oxygen sensor. A value of 0 mA indicates a well-balanced air: fuel ratio. Positive current indicates a lean mixture, and negative current indicates a rich mixture.
2.2.5. Short Term Fuel Trim
Short term fuel trim involves on-the-spot changes the computer makes in response to the oxygen sensor. The computer compensates for lean mixtures by adding fuel and for rich mixtures by leaning the fuel mixture out.
2.2.6. Long Term Fuel Trim
Long term fuel trim represents the percentage of ECM adjustments that calculates the quantity of fuel to be injected into the cylinders to compensate for changes over a longer period.
- Note: Changes in Long Term Fuel Trim only take seconds to update and are permanently stored in the ECM memory.
2.2.7. Commanded Equivalence Ratio
Commanded equivalence ratio (CER), also known as lambda, determines the air and fuel ratio requested by the ECM.
- Wide Range O2 Sensored Vehicles: CER is displayed in both open and closed loop mode.
- Conventional O2 Sensored Vehicles: CER is displayed in open loop mode and shows 1.0 in closed loop mode.
2.2.8. Mass Air Flow Rate
Mass airflow rate is the value measured by a vehicle MAF sensor, which should be within the range from 2 to 7 g/s at idle and rise to between 15 to 25 g/s at 2500 rpm.
- Note: Refer to your manufacturer’s specifications to ensure your vehicle’s airflow rate.
2.2.9. Intake Air Temperature
Intake air temperature (IAT) is the value of the temperature that travels through the engine cylinders. There are 3 IAT sensors in a vehicle with different functions:
- To measure the air that enters the engine.
- To measure the climate control system of a vehicle.
- To measure the ambient air temperature.
2.2.10. Intake Manifold Absolute Pressure
Intake manifold absolute pressure (MAP) is measured by a MAP Sensor inside the intake. It works with the intake air pressure to determine the amount of air and fuel to ignite the cylinders.
- Running Engine: 18 – 20 “Hg intake manifold vacuum.
- Idle Engine: 0 – 20 “Hg intake manifold vacuum.
2.2.11. Fuel Pressure (Gauge)
Fuel pressure value as a gauge value. A value of 0 indicates atmospheric/ambient pressure.
2.2.12. Fuel Rail Pressure
Pressure in the fuel rail displayed as a gauge value (0 psi/kPa means an atmospheric/ambient pressure reading).
2.2.13. Fuel Rail Pressure (Absolute)
Pressure in the fuel rail displayed as an absolute pressure value. When the fuel rail is not pressurized, this data point will display ambient pressure (roughly 14.7 psi or 101.3 kPa).
2.2.14. Fuel Rail Pressure (Relative to Manifold Vacuum)
Fuel pressure value relative to the intake manifold vacuum. This parameter helps diagnose fuel delivery issues under different engine load conditions.
2.2.15. Alcohol Fuel %
The ethanol/alcohol content as measured by the engine computer in percentage. For example, an E85 blend would show 85% for alcohol fuel percentage.
2.2.16. Fuel Level Input
Percent of maximum fuel tank capacity. This parameter provides a direct reading of the fuel level, aiding in diagnosing fuel gauge issues.
2.2.17. Engine Fuel Rate
Near-instantaneous fuel consumption rate, expressed in Liters or Gallons per hour. Engine fuel rate is calculated by the ECM using the volume of fuel used during the last 1000 ms.
- Note: Engine fuel rate does not include fuel consumed by diesel aftertreatment systems.
2.2.18. Cylinder Fuel Rate
The calculated amount of fuel injected per cylinder during the most recent intake stroke, displayed in mg/stroke.
2.2.19. Fuel System Percentage Use
This parameter displays the % of total fuel usage for each cylinder bank, up to a maximum of four banks. This data point will display data for two separate fuel systems (e.g., diesel & CNG) if supported by the vehicle.
2.2.20. Fuel Injection Timing
The angle (in degrees) of crankshaft rotation before top dead center (BTDC) at which the fuel injector begins to operate. A positive angle indicates injector operation before top dead center, while a negative angle indicates operation on the downstroke after TDC.
2.2.21. Fuel System Control
This parameter reports the following status information for the fuel system on diesel vehicles (for fuel systems 1 & 2 as supported by the vehicle):
- Fuel pressure control: Closed or open loop control
- Fuel injection quantity: Closed or open loop control
- Fuel injection timing: Closed or open loop control
- Idle fuel balance/contribution: Closed or open loop control
Closed loop indicates the system is using sensor feedback for fine tuning.
- Note: Systems 1 & 2 refer to two separate fuel systems – system 2 may not be in use on most vehicles.
2.2.22. Fuel Pressure Control System
This parameter displays the following data for up to two fuel rails – for sensor location refer to your factory manual:
- Commanded rail pressure
- Actual rail pressure
- Temperature
Pressure is reported as a gauge pressure where 0 indicates rail pressure equal to the outside atmosphere.
2.2.23. Injection Pressure Control System
Some diesels use a pump to pressurize an oil rail which then transfers and multiplies this pressure via a piston to provide finer control over fuel injection pressures. The ICP sensor monitors the pressure on the oil side of the fuel system. Depending on the vehicle, this parameter will display:
- Commanded Control Pressure Rail A
- Actual Pressure Rail A
- Commanded Control Pressure Rail B
- Actual Pressure Rail B
2.2.24. Boost Pressure Control
Depending on the vehicle, this parameter will show the following for one or two turbochargers:
- ECM commanded boost pressure
- Actual boost pressure
- Note: All data in this parameter is reported in absolute pressure.
This parameter will also provide feedback on the operating mode of the boost control system, possible states are:
- Open Loop – No sensor feedback used, no faults present
- Closed Loop – Using sensor feedback, no faults present
- Fault Present – Boost data unreliable
2.2.25. Turbocharger RPM
Measured turbine RPM of one or both turbos depending on vehicle configuration.
- Note: This data point has a maximum value of 655,350 rpm, so you may need to adjust your graph range settings when monitoring data in-app or it may appear as a straight line.
2.2.26. Turbocharger Temperature
This parameter reports the following data for one or both turbochargers as supported by the vehicle:
- Compressor inlet temperature – Air charge temperature before the turbo
- Compressor outlet temperature – Air charge temperature at the turbo outlet – this value should be much higher
- Turbine inlet temperature – Exhaust temperature pre-turbo
- Turbine outlet temperature – Exhaust temperature post-turbo
Charge air temperatures have a range from -40 to 215 degC, while the exhaust temperature reporting range is -40 to 6513.5 degC.
2.2.27. Turbocharger Compressor Inlet Pressure Sensor
Pressure measured at the turbocharger inlet, for either one or two turbos depending on vehicle configuration. This is an absolute pressure value; a value of roughly 14.7 psi / 101.3 kPa indicates atmospheric pressure.
2.2.28. Variable Geometry Turbo (VGT) Control
Vehicles with variable geometry turbos use motors or another method of actuation to change the orientation of vanes which will either direct the exhaust gasses around, or through the turbine blades. The VGT parameter displays data related to the position/orientation of these vanes in the turbocharger. A value of 0% indicates that the vanes are in the maximum bypass position, while at 100% the vanes redirect as much exhaust gas as possible to build boost.
VGT Control displays the following information for one or both turbos depending on vehicle configuration:
- Commanded VGT Position – Vane position requested by the vehicle
- Actual VGT Vane Position
- VGT Control Status: Closed or Open Loop (using sensor feedback or not) without system faults or in a Fault State (VGT position data is unreliable)
2.2.29. Wastegate Control
The wastegate allows exhaust gas to bypass the turbo as boost builds to prevent excessive pressure. This parameter reports the following information for electronic wastegate systems (one or two depending on the vehicle configuration):
- Commanded wastegate position as requested by the controller – 0% represents fully closed (all exhaust routed through the turbo), and 100% indicates maximum diversion around the turbine section.
- Actual wastegate position – 0% to 100%
2.2.30. Charge Air Cooler Temperature (CACT)
This parameter reports the temperature of the intercooler air charge on turbocharged vehicles with up to four sensors:
- Bank 1 Sensor 1
- Bank 1 Sensor 2
- Bank 2 Sensor 1
- Bank 2 Sensor 2
The SAE/OBDII standard does not specify a default mapping for these data points, so you may need to refer to the factory manual for your vehicle to determine sensor/measurement locations.
2.3. Emissions Control-Related Parameters
2.3.1. Commanded EGR
How open the EGR valve should be as requested by the engine computer (0% fully closed, 100% fully open).
2.3.2. EGR Error
The percent difference between the commanded EGR opening and the actual opening of the EGR valve.
Special Note: If commanded EGR is 0%, EGR error will read:
- 0% if actual EGR is also 0%
- 99.2% if actual EGR is anything other than 0% – this indicates “undefined” or not applicable
EGR error is calculated as (actual – commanded)/commanded. A commanded value of 0% gives (0-0)/0 = 0%. With any other ‘commanded’ value, the calculation becomes (actual-0)/0, which is undefined.
2.3.3. Commanded Diesel Intake Air Flow Control
Also referred to as EGR Throttle. Some newer diesels may employ a throttle plate to generate an intake vacuum under some conditions for the purpose of introducing EGR gasses to reduce emissions. This data point displays (if supported by the vehicle):
- The commanded (closed to 100% open) position of the intake air flow throttle plate
- The actual position of the EGR throttle
- Commanded position of a second EGR throttle if fitted
- Actual position of secondary EGR throttle
2.3.4. Exhaust Gas Recirculation Temperature
This parameter reports up to four EGR temperature values:
- EGRTA – Bank 1 Pre-Cooler
- EGRTB – Bank 1 Post-Cooler
- EGRTC – Bank 2 Pre-Cooler
- EGRTD – Bank 2 Post-Cooler
2.3.5. EVAP System Vapor Pressure
Gauge pressure of the EVAP system measured from either a sensor in the fuel tank or evap system line. See your factory manual or a parts diagram for sensor location.
2.3.6. Absolute Evap System Vapor Pressure
Absolute pressure of the EVAP system measured from either a sensor in the fuel tank or evap system line (see your factory manual for vehicle specific measurement point). This is an absolute pressure measurement; a value of roughly 14.7 psi or 101.3 kPa indicates 0 gauge pressure relative to outside ambient conditions.
2.3.7. Commanded Evaporative Purge
EVAP purge flow rate requested by the engine computer:
- 0% fully closed
- 100% maximum
2.3.8. Catalyst Temperature
Temperature of the catalytic converter. Bank # indicates the ‘side’ of the engine (typically bank 1 will be on the same side as cylinder #1). Sensor # indicates whether the sensor is pre (#1) or post (#2) cat.
2.3.9. Diesel Aftertreatment Status
The Diesel Particulate Filter is used for trapping soot and reducing exhaust emissions on diesel vehicles. As soot accumulates, the filter will become ‘clogged,’ and the pressure drop across the filter will increase (see ‘Diesel Particulate Filter’). When the filter reaches a set criteria, it must be ‘regenerated’ – the soot is burned off through various methods so that the filter can be used again.
DPF Regeneration can be:
- Passive – using standard exhaust temperature while driving
- Active – using fuel injection to increase the exhaust temperature
- Forced – triggered using a factory scan tool before the regen criteria of the vehicle is met
NOx adsorption involves the use of various substances in the exhaust to ‘trap’ Nitrous Oxide. Unlike with SCR, there is no consumable fluid that needs to be topped up, but as the NOx ‘trap’ reaches capacity, it must be regenerated. NOx absorber regeneration involves exposing the ‘trap’ to a reductant such as fuel or hydrogen, which reacts with the NOx to produce N2 and water. Over time, SOx will also build up in the NOx adsorption system, which requires a high-temperature ‘desulfurization’ process to restore the system to operating conditions.
This is a hybrid data point capable of display the following (if supported by your vehicle):
- Current DPF Regeneration Status: Active/Not Active
- Current DPF Regeneration Type: Passive/Active
- NOx Absorber Regen Status: Active/Not Active
- NOx Absorber Desulfurization Status: Active/Not Active
- Normalized Trigger for DPF Regen: The percentage until the next regen event – 0% means a regen has just completed, while 100% indicates one is about to start
- Average Time Between DPF Regens: The exponential weighted moving average time between regen events, indicating a representative value over the last 6 events
- Average Distance Between DPF Regens: The exponential weighted moving average distance driven between regen events, indicating a representative value over the last 6 events
2.3.10. Diesel Exhaust Fluid Sensor Data
This parameter will display the following information (as supported by the vehicle):
- DEF Type: Urea too high, Urea too low, Straight diesel, Proper DEF, Sensor fault
- DEF Concentration: Urea concentration – should display roughly 32.5% for proper DEF
- DEF Tank Temperature
- DEF Tank Level – Important note: tank level may not change progressively.
2.3.11. Diesel Particulate Filter (DPF)
This parameter reports up to three separate data points:
- Inlet pressure
- Outlet pressure
- Differential pressure across the particulate filter
An increase in differential pressure indicates that soot is accumulating in the filter, possibly indicative of an upcoming regeneration event. Bank 1 vs 2 indicate the ‘side’ of the engine – bank #1 will be on the same ‘side’ of the engine as cylinder #1.
2.3.12. Diesel Particulate Filter (DPF) Temperature
This parameter reports up to two data points for the particulate filter on each exhaust bank:
- Inlet temperature
- Outlet temperature
Bank 1 vs 2 indicate the ‘side’ of the engine – bank #1 will be on the same ‘side’ of the engine as cylinder #1.
2.3.13. NOx Sensor
This hybrid parameter reports the NOx concentration levels in ppm of the following sensors (if supported):
- Bank 1 Sensor 1
- Bank 1 Sensor 2
- Bank 2 Sensor 1
- Bank 2 Sensor 2
Bank # indicates the ‘side’ of the engine for this exhaust – bank #1 is on the same side of the engine as cylinder #1. Sensor number indicates whether the sensor is situated before (#1) or after (#2) the NOx adsorption system.
2.3.14. NOx Control System
This hybrid parameter reports the following data on the NOx adsorption system (as supported by the vehicle):
- Average Reagent Consumption Rate – Calculated either over the previous 48 hours of engine run time or the last 15L consumed (whichever is a longer period). This value will be reported as 0 when the key is on with the engine off.
- Average Demanded Consumption Rate – As commanded by the ECM, calculated either over the previous 48 hours of engine run time or the last 15L consumed (whichever is a longer period). This value will be reported as 0 when the key is on with the engine off.
- Reagent Tank Level – 0 to 100%
Note: Depending on the vehicle, tank level might not display a progressive value between 100% and 0% as fluid is consumed – tank level may only display values at specific measurement points.
If a vehicle is not capable of reporting true tank level at all times, it will show the average between each discrete step when not measuring that exact level.
For example, consider a vehicle that is only capable of directly measuring three tank levels: full at 100%, low at 20%, empty at 0%. As fluid is consumed to depletion over time, this data point will report:
- 100% when full
- 60% while the actual fluid level is between 20% and 100%
- 20%
- 10% while actual level is between 0% and 20%
- 0% at empty
- NOx Warning Indicator Time – Total engine run time in seconds since the NOx/SCR (DEF etc) warning light has activated on the dash. This data point will start at 0 when the NOx warning light comes on and count up for every second of engine run time that the light is on – to a maximum of 136 years.
Once the NOx light goes out, the counter will stop increasing, and it will reset if the light comes back on or 9600 engine-hours pass without the light activating again.
2.3.15. NOx Sensor Corrected Data
NOx concentration in PPM including learned adjustments and offsets.
2.3.16. NOx NTE Control Area Status
The NOx ‘not to exceed control area’ is a range of engine operation (speed and load) in which emissions are sampled and tested vs governmental NOx limits.
In addition, automakers may petition the governing body for special vehicle specific exemptions for engine operation envelopes that may normally fall within the NTE test range, but that they believe should not apply. If this exception is granted, a ‘carve-out area’ of the engine operating envelope may be defined, in which NTE limits do not apply for this specific vehicle.
This parameter displays (as supported by the vehicle):
- Whether the vehicle is operating inside or outside the NOx control area
- Whether the vehicle is operating inside the manufacturer exception/’carve-out’ region
- Whether the vehicle is experiencing an NTE related deficiency within the NOx operating control area
2.3.17. PM Sensor Bank 1 & 2
This parameter reports the following data (as supported by the vehicle) for banks 1 & 2:
- Particulate matter sensor active: yes/no
- Particulate matter sensor regenerating: yes/no
- Particulate matter sensor value: 0% (clean) to 100% (regen required)
2.3.18. Particulate Matter (PM) Sensor
The soot concentration as measured by the particulate matter sensors on banks 1 & 2 – displayed in mg/m3.
2.3.19. PM NTE Control Area Status
The PM ‘not to exceed control area’ is a range of engine operation (speed and load) in which emissions are sampled and tested vs governmental particulate matter emission limits.
In addition, automakers may petition the governing body for special vehicle-specific exemptions for engine operation envelopes that may normally fall within the NTE test range, but that they believe should not apply. If this exception is granted, a ‘carve-out area’ of the engine operating envelope may be defined, in which NTE limits do not apply for this specific vehicle.
This parameter displays (as supported by the vehicle):
- Whether the vehicle is operating inside or outside the PM control area
- Whether the vehicle is operating inside the manufacturer exception/’carve-out’ region
- Whether the vehicle is experiencing an NTE related deficiency within the PM operating control area
2.3.20. SCR Inducement System
Selective Catalytic Reduction is used on diesel engines to reduce the amount of NOx in the exhaust using a catalyst and reductant/reagent (often urea or ammonia).
Inducement refers to strategies employed by the vehicle to alert drivers that there is an issue with the SCR system requiring their attention. Depending on the vehicle, this may be a dash light, cluster message, or functional restriction (torque reduction/limp mode, speed limiter, etc.).
SCR inducement will be triggered by one or more of the following:
- Low reagent level
- Incorrect reagent used (e.g., water instead of DEF)
- Abnormal reagent consumption rates
- Excessive NOx emissions
This parameter will report current SCR inducement status (on or off) as well as the reasons for activation. Additionally, it will show whether any of the above have occurred during the the last:
- 0 – 10,000 km
- 10,000 – 20,000 km
- 20,000 – 30,000 km
- 30,000 – 40,000 km
Depending on the vehicle, it may also report the total distance traveled during each 10,000 km block above with the inducement system active.
2.3.21. NOx Warning And Inducement System
This parameter displays information on warning/inducement levels – for more information on inducements, see SCR Induce System. Warning/inducement levels are broken down into three levels:
- Level 1 – Low severity, e.g., minor power/torque reduction
- Level 2 – Medium severity, e.g., significant power/torque reduction (limp mode)
- Level 3 – Severe, e.g., complete engine shut down, extreme operational limits
Each level will report one of the four following statuses:
- Inactive
- Enabled, but not active (triggered – but not taking effect yet)
- Active
- Not supported by vehicle
This parameter will also report (as supported):
- Total engine hours using incorrect reagent
- Total engine hours with incorrect reagent consumption rate
- Total engine hours during which reagent dosing was interrupted (
