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Understanding CARB’s Clean Truck Check OBD Readiness Requirements

And avoiding costly Clean Truck Check failures

At Clean Truck Check Pro, we understand that navigating California's air quality regulations can be challenging for heavy-duty vehicle owners.

One crucial aspect of these regulations is the On-Board Diagnostics (OBD) readiness requirements set by the California Air Resources Board (CARB) for the Clean Truck Check program.

In this page, we'll explain these requirements and provide important tips to help you avoid common pitfalls that can lead to failed inspections, DMV registration holds and expensive vehicle down-time.

What are CARB’s OBD Readiness Requirements?

The OBD system in your heavy duty vehicle is designed to monitor the performance of your vehicle's emissions control system. CARB’s Clean Truck Check program uses this system to ensure that vehicles meet emissions standards and are operating correctly.

If your vehicle’s Malfunction Indicator Light (MIL) is on, it will automatically fail the Clean Truck Check inspection.

Key Points to Remember

Manual MIL Resets Lead to Failure

If you manually reset the MIL without addressing the underlying issue, your vehicle will likely fail the inspection. The OBD system tracks vehicle performance, and simply turning off the light does not fix the problem.

Post-Repair Readiness

If your vehicle had an active MIL due to an issue that was repaired, the vehicle must still meet the OBD readiness criteria to pass the inspection. This means the system needs to confirm that the vehicle has been driven enough to verify that all emission-related systems are functioning correctly.

Specific OBD Readiness Criteria You Need to Know

To pass the Clean Truck Check, your vehicle must meet specific OBD readiness criteria, which include:

1. Warm-Up Cycles

The vehicle must complete a certain number of warm-up cycles, which involve starting the vehicle from a cold state and bringing it up to operating temperature. This ensures that the vehicle’s emission systems are working properly under normal driving conditions.

2. Miles Driven

After a repair or MIL reset, the vehicle must be driven a minimum number of miles to allow the OBD system to complete its self-diagnostic tests. Typically, this requires driving between 50 and 100 miles, but it can vary depending on the vehicle and the specific issue.

3. Engine Run Time

In addition to mileage, the vehicle must run for a certain number of hours to ensure all necessary OBD system checks are completed. This helps verify that all emission control systems are operating as intended.

Current Program Leniency and Future Changes

Currently, CARB's Clean Truck Check program is in its initial phases, and the OBD readiness criteria are not as stringent as they will be in the future.

Some vehicles may pass the inspection even if they do not fully meet the minimum readiness criteria. However, it is important to note that these criteria will become stricter as the program matures.

Future phases of the program will likely require full compliance with all readiness criteria, meaning vehicles that do not meet these standards will fail the inspection.

Clean Truck Check pass results, with a warning that OBD readiness was not met.

Why It’s Important to Schedule Your Clean Truck Check Early

Getting your Clean Truck Check done before the due date is crucial for several reasons:

1. Time for Repairs

If your vehicle fails the Clean Truck Check, you will need time to make the necessary repairs and achieve the OBD readiness criteria. Waiting until the last minute can lead to delays, fines, and registration holds if the repairs take longer than expected.

2. 90-Day Inspection Window

According to CARB, you can perform the Clean Truck Check up to 90 days before it is due. This gives you plenty of time to address any issues that may arise during the inspection, reducing the risk of costly downtime for your vehicle.

Tips to Ensure Your Vehicle Meets OBD Readiness Criteria

To help ensure that your vehicle is ready for its Clean Truck Check, follow these tips:

1. Regular Maintenance

Keep up with regular vehicle maintenance and address any issues as soon as they arise. This will help prevent the MIL from turning on due to overlooked problems.

2. Drive Your Vehicle After Repairs

If you’ve recently repaired an issue that caused the MIL to turn on, make sure to drive your vehicle for a sufficient period. The OBD system needs time to run its self-tests and confirm that all emission-related systems are functioning correctly.

3. Avoid Resetting the MIL Manually

Manually resetting the MIL without fixing the underlying issue will not clear the problem from the OBD system’s memory. Your vehicle must undergo a proper repair and then complete a driving cycle that allows the OBD system to verify that the repair was successful.

Stay Ahead of the Game with Clean Truck Check Pro

At Clean Truck Check Pro, we’re here to help you stay compliant with CARB regulations and avoid any unexpected issues with your Clean Truck Check. By understanding the OBD readiness requirements and taking proactive steps, you can ensure your vehicle passes the inspection the first time, every time.

Need to Schedule a Clean Truck Check?

If you have questions or need to schedule a Clean Truck Check inspection, don’t hesitate to contact us. Our phone number is (323) 929-7570, or you can book an Clean Truck Check inspection online.

Clean Truck Check Pro

Our mobile diesel "smog" test service is based in Los Angeles, California. Our service area includes Los Angeles County, Orange County, Ventura County and Southern Santa Barbara County. We offer Clean Truck Check inspections on 2013 and newer diesel, hybrid and alt-fuel vehicles.