If you’ve encountered a “Obdii Not Ready For Testing” message during a smog or emissions inspection, it can be frustrating and confusing. This status indicates that your vehicle’s On-Board Diagnostic System (OBDII) hasn’t completed all the necessary self-tests, meaning it’s not ready to accurately assess your car’s emissions performance. As an auto repair expert at autelfrance.com, I’m here to explain what this means and how you can get your vehicle ready for testing.
Understanding OBDII Readiness Monitors
Modern vehicles are equipped with sophisticated OBDII systems that continuously monitor various engine and emission control components. These monitors run self-tests to ensure everything is functioning correctly. When these tests are complete and pass, the monitors are set to a “ready” or “complete” status. However, if these monitors haven’t run or haven’t completed their tests, they will show as “not ready” or “incomplete.”
There are two main categories of OBDII monitors:
- Continuous Monitors: These run constantly while the engine is operating. They include the Misfire Monitor, Fuel System Monitor, and Comprehensive Components Monitor. These are usually ready at all times unless there’s a fault.
- Non-Continuous Monitors (or Readiness Monitors): These monitors require specific driving conditions to run their tests. Common readiness monitors include:
- Catalyst Monitor: Checks the efficiency of the catalytic converter.
- Evaporative System (EVAP) Monitor: Tests for fuel vapor leaks in the EVAP system.
- Oxygen Sensor Monitor: Evaluates the performance of the oxygen sensors.
- Secondary Air System Monitor: (If applicable) Checks the secondary air injection system.
- Heated Catalyst Monitor: (If applicable) Monitors the heated catalytic converter.
- EGR System Monitor: (If applicable) Tests the Exhaust Gas Recirculation system.
For an emissions test to pass, most vehicles are allowed to have one or two “not ready” monitors (depending on the model year and local regulations). However, in many areas, all monitors must be ready for the vehicle to pass inspection.
Common Reasons for OBDII Monitors Not Ready
Several factors can cause OBDII monitors to be in a “not ready” state:
- Recent Battery Disconnection or Replacement: Disconnecting the car battery, even for a short period, will reset the OBDII system and erase the readiness monitor status. The monitors will need to run their tests again.
- Clearing Diagnostic Trouble Codes (DTCs): Using a scan tool to clear engine codes also resets the readiness monitors. Even if the underlying issue is fixed, the monitors need to re-run.
- Recent Vehicle Repairs: Certain repairs, especially those related to the emission system or engine management, can reset the monitors.
- Fault Codes or Underlying Issues: If there are unresolved fault codes or underlying mechanical problems, some monitors might not be able to complete their tests and will remain “not ready.”
- Interrupted Drive Cycles: The readiness monitors require specific driving patterns, known as drive cycles, to run effectively. If these drive cycles are interrupted or not completed correctly, the monitors may not set.
- Cold Weather Conditions: In extremely cold temperatures, some monitors, particularly the EVAP monitor, might not run due to temperature-sensitive components.
The Drive Cycle Solution: Getting Your Monitors Ready
A “drive cycle” is a pre-defined set of driving conditions that are designed to allow the OBDII readiness monitors to run and complete their self-tests. Performing a drive cycle is often necessary after a battery disconnection or code clearing to get your car ready for an emissions test.
While specific drive cycles vary depending on the vehicle make, model, and engine type, they generally involve a combination of:
- Cold Start: Starting the engine after it has been completely cooled down (typically overnight).
- Idling: Letting the engine idle for a specific period.
- Steady Speed Cruising: Driving at consistent speeds for a certain duration.
- Acceleration and Deceleration: Varying speeds and engine load.
Here’s an example of a drive cycle, similar to the one mentioned for a Toyota MR2 with a 2AZ-FE engine, which can give you an idea of what’s involved:
- Cold Start: Ensure the engine is cold. Start the engine and let it idle for approximately 10 minutes.
- Moderate Speed Driving: Drive at a steady speed between 43-56 mph (70-90 km/h) for 3-5 minutes, maintaining engine speed between 900 and 3,200 rpm.
- Idling Again: Stop the vehicle and idle for 3-5 minutes.
- Repeat Moderate Speed and Idle: Repeat steps 2 and 3 once.
- Slightly Lower Speed Driving: Drive at 40-55 mph (65-90 km/h) for 3 minutes.
- Lower Speed Driving: Drive at 35-45 mph (55-70 km/h) for 7 minutes.
- Fuel Tank Pressure Release: Stop the vehicle, turn off the engine, and release fuel tank pressure by briefly removing and reinstalling the fuel cap.
- Moderate Speed Driving (Again): Start the engine and drive at approximately 45 mph (70 km/h) for 5 minutes.
- Lower Speed with Stops: Drive at approximately 25 mph (40 km/h) for 15 minutes, including at least two stops of about 30 seconds each.
- Idle for 2 Minutes: Stop and idle the engine for 2 minutes.
- Short Drive with Idle: Drive at 25 mph (40 km/h) or more for at least 50 seconds, ensuring engine speed is above 900 rpm.
- Idle for 40 Seconds: Stop and idle for at least 40 seconds.
- Repeat Short Drive/Idle Cycle: Repeat steps 11 and 12 ten times.
A budget-friendly OBDII scanner like the Autel MS309 can help you check your vehicle’s readiness monitor status.
Important Considerations for Drive Cycles:
- Vehicle-Specific Drive Cycle: The drive cycle above is just an example. It’s crucial to find the specific drive cycle recommended for your vehicle’s make, model, and year. You can usually find this information in your owner’s manual, repair information websites, or by searching online for “[Your Vehicle Make and Model] drive cycle.”
- Safety First: Perform drive cycles in safe locations, obeying all traffic laws. Avoid aggressive driving or exceeding speed limits.
- Patience and Repetition: It might take more than one drive cycle to set all monitors to “ready.” If the monitors are still not ready after one attempt, ensure you’ve followed the procedure correctly and try again.
- Check Engine Light: If your check engine light is on, address the underlying issue first before attempting a drive cycle. A persistent fault can prevent monitors from setting.
Using a Scanner to Check Readiness Monitor Status
The most effective way to check if your OBDII monitors are ready is to use an OBDII scanner. These tools plug into your vehicle’s diagnostic port and can display the status of each monitor (ready or not ready).
Affordable scanners like the Autel MS309 (linked in the original article) are excellent for basic OBDII diagnostics and checking readiness monitor status. More advanced scanners offer even more features, such as reading and clearing codes, live data streaming, and advanced diagnostic capabilities.
Checking your readiness status with a scanner saves you from guessing and ensures you know when your vehicle is actually ready for an emissions test.
When to Seek Professional Help
If you’ve performed several drive cycles, checked for fault codes, and your OBDII monitors are still “not ready,” it’s time to seek professional help from a qualified mechanic. There might be an underlying mechanical or electrical issue preventing the monitors from completing their tests. A professional technician can diagnose the problem accurately and perform the necessary repairs to get your vehicle ready for testing.
In conclusion, understanding why your OBDII system might be “not ready for testing” and how to perform a drive cycle is crucial for vehicle owners. By following the right procedures and utilizing diagnostic tools when needed, you can often resolve this issue and ensure your vehicle passes its emissions inspection. Remember to prioritize safety and consult a professional if you encounter persistent problems.
