Understanding the On-Board Diagnostic (OBDII) system and its monitors is crucial for vehicle owners and technicians in California to ensure compliance with the state’s stringent emission standards. California’s Smog Check program relies heavily on OBDII testing to identify vehicles that are polluting excessively. This guide provides a detailed overview of the Obdii Monitors Required For California Emissions testing, pass/fail standards, and common issues that can arise during inspections.
Readiness Monitor Standards for California Smog Check
Readiness monitors are self-diagnostic tests performed by a vehicle’s OBDII system to confirm that emission control systems are functioning correctly. These monitors run under specific driving conditions, and their status (complete or incomplete) is a key factor in passing or failing the OBDII portion of a California Smog Check. For vehicles registered in California, ensuring these monitors are in a ‘ready’ state before a smog test is essential for compliance with obdii monitors required for california emissions.
The number of incomplete readiness monitors allowed varies based on the vehicle model year and fuel type, as detailed in the table below:
OBDII Readiness Monitor Pass/Fail Standards in California
| Model Year | Fuel Type | Number of Incomplete Monitors Allowed to Pass OBD Test |
|---|---|---|
| 1996-1999 | Gas | Any one |
| 2000 and newer | Gas | Evaporative system |
| 1998-2006 | Diesel | Zero |
| 2007 and newer | Diesel | Particulate Filter and Non-Methane HydroCarbon (NMHC) |
It’s important to note that for gasoline vehicles, the misfire, fuel, and comprehensive component continuous monitors are disregarded during the OBDII test. For diesel vehicles manufactured in 2007 and later, the Particulate Filter and NMHC monitors are specifically considered when determining pass/fail status related to incomplete monitors.
This table illustrates the specific number of incomplete OBDII monitors permitted for different vehicle model years and fuel types to pass the California Smog Check, emphasizing the stringent requirements for diesel vehicles and modern gasoline vehicles.
Malfunction Indicator Lamp (MIL) Standards in California OBDII Tests
The Malfunction Indicator Lamp (MIL), commonly known as the “Check Engine” light, is a critical component of the OBDII system. Its behavior during a Smog Check is a direct indicator of potential emission control issues. In California, the MIL standards for the OBDII test are straightforward:
MIL Operation Standards for California Smog Check
| Condition | Pass/Fail | Standard |
|---|---|---|
| Key On Engine Off (KOEO) | Pass | MIL illuminates |
| Engine Running (KOER) | Pass | MIL turns off |
| Key On Engine Off (KOEO) | Fail | MIL does not illuminate |
| Engine Running (KOER) | Fail | MIL illuminates |
A properly functioning MIL should illuminate when the ignition is turned on but the engine is not running (KOEO) to indicate it is working. Once the engine is started (KOER), the MIL should turn off if no active emission-related faults are detected. Failure in either of these states results in a Smog Check failure in California, highlighting the importance of addressing any “Check Engine” light issues to meet obdii monitors required for california emissions.
This table clearly defines the expected behavior of the Malfunction Indicator Lamp (MIL) during a California Smog Check, outlining the conditions for passing and failing based on MIL illumination status.
Communication Standards for OBDII Testing in California
Successful communication with the vehicle’s OBDII system is a fundamental requirement for the Smog Check. A failure to communicate can stem from various issues, ranging from a faulty OBDII connector to more complex electronic problems. California’s Bureau of Automotive Repair (BAR) mandates specific communication standards for both BAR-97 and OIS (On-Board Inspection System) inspections.
OBDII Communication Standards for California Smog Check
| Vehicle | Inspection System | Standard |
|---|---|---|
| All with OBDII | BAR-97 | Vehicle communicates with BAR-97 |
| All with OBDII | OIS | Vehicle communicates with OIS and transmits required data |
For OIS inspections, “required data” typically includes information from OBD addresses Mode $01 PID $00 and Mode $01 PID $01. This data provides details on supported OBD data and includes MIL status, Diagnostic Trouble Codes (DTCs), and monitor status. Ensuring proper OBDII communication is the first step in verifying compliance with obdii monitors required for california emissions.
This table specifies the communication standards that vehicles must meet during a California Smog Check, depending on whether the inspection is conducted using a BAR-97 or OIS system.
Permanent Diagnostic Trouble Code (PDTC) Standards in California
Permanent Diagnostic Trouble Codes (PDTCs) are a type of DTC that, once set, cannot be cleared by simply using a scan tool or disconnecting the battery. PDTCs are designed to ensure that a vehicle has truly resolved an emission issue before passing a Smog Check. California added PDTC checks to the BAR-OIS Smog Check inspection on July 1, 2019.
PDTC Pass/Fail Standards for California OIS Inspections
| Model Year | Inspection System | Standard |
|---|---|---|
| 1996-1999 | BAR-97 | Not applicable |
| 2000-2009 | OIS | Not applicable |
| 2010 and newer | OIS | Vehicles fail when a PDTC is present |
Vehicles from model year 2010 and newer will fail a California Smog Check if any PDTCs are present, regardless of whether the MIL is illuminated. However, there are exceptions: PDTC presence is ignored if the vehicle has completed at least 15 warm-up cycles and been driven at least 200 miles since its OBD information was last cleared. This PDTC check is a significant aspect of verifying obdii monitors required for california emissions compliance in newer vehicles.
This table clearly defines the PDTC standards for California Smog Checks, indicating that vehicles from 2010 onwards will fail if PDTCs are present, emphasizing the importance of resolving underlying issues.
Vehicles with Known OBDII Monitor Issues in California Smog Checks
Certain vehicle makes and models are known to have specific issues that can affect their ability to pass the OBDII portion of a California Smog Check. These issues can range from communication problems to incomplete readiness monitors or problems with Permanent Diagnostic Trouble Codes. The California Bureau of Automotive Repair provides resources to help technicians address these “Vehicles of Interest”. These issues are crucial to understand when dealing with obdii monitors required for california emissions in specific vehicles.
Common OBDII Issues and Affected Vehicles:
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Communication Problems: Some vehicles, particularly certain Ford Escape, Bronco Sport, and E-Series models, and older Audi and VW models, may experience no communication or intermittent communication with the Smog Check testing equipment. This can be due to software glitches, wiring issues, or module problems. For instance, certain Ford models may require software updates at the dealership to resolve gateway module communication issues. Older Audi and VW vehicles might suffer from broken ground wires in the ABS module, disrupting communication.
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Incomplete Readiness Monitors: Many vehicles are listed as having difficulties setting specific readiness monitors. BMW models from the late 1990s and early 2000s are frequently cited for oxygen sensor monitor issues requiring DME software reprogramming. Chevrolet S-10 and GMC Sonoma flex-fuel models from the early 2000s may have monitors disabled due to ethanol content. Various Dodge/Ram diesel trucks, especially those over 8,500 GVWR from the late 1990s and early 2000s, may not be OBDII certified or have monitors that don’t complete, requiring specific handling during the Smog Check. Ford Focus models from 2003 and certain Mazda 6 models may also have monitors that are difficult to set. Jaguar and Land Rover diesel models from 2017-2019 have been noted for NOx aftertreatment monitor issues, often requiring dealer software updates.
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Permanent Diagnostic Trouble Code (PDTC) Issues: Certain Chrysler, Dodge, Jeep, and Ram models from the early to mid-2010s are known to have PDTCs that may not clear, even after repairs. This is often due to software issues requiring PCM reflashing, sometimes covered under recalls or extended warranties. Specific PDTC codes, like P0315 in Ford Mustangs or P1D30 in Jeep and Ram diesel models, are flagged as potential issues requiring specific attention during inspections. Audi and Volkswagen TDI diesel models from the early 2010s may have certain PDTCs (like P0087, P0088, P053F) that are persistently present and are often ignored by the OIS system due to a lack of remedy.
It’s crucial for Smog Check technicians to be aware of these vehicle-specific issues and consult resources like the BAR On-Board Diagnostic Test Reference for detailed instructions and potential remedies. For vehicle owners, understanding these common problems can help in proactively addressing potential issues before a Smog Check to ensure compliance with obdii monitors required for california emissions.
Modified Software Standards and California Smog Check
California’s Smog Check program also includes a check for modified software. Vehicles identified with illegally modified software that bypasses or defeats emission controls will fail the inspection. This measure, implemented in July 2021, aims to prevent tampering with vehicle software for emissions purposes. Only software updates approved by the California Air Resources Board (CARB) through an Executive Order are permissible. This is another layer of ensuring vehicles meet the obdii monitors required for california emissions standards in California.
Conclusion: Ensuring OBDII Monitor Compliance for California Emissions
Successfully navigating the OBDII portion of a California Smog Check requires a thorough understanding of readiness monitors, MIL operation, communication protocols, and PDTC standards. Vehicle owners and technicians must be aware of the specific obdii monitors required for california emissions and address any issues proactively. Consulting official resources and staying updated on vehicle-specific problems are essential steps in maintaining compliance and contributing to cleaner air in California.
