2002 Cavalier had engine light on. Catalytic converter had to be replaced. That was done and then the car was inspected. Engine light is off and inspector said that 2 sensors were still showing that the car had not reset. I was told to drive it 100 miles. Drove over 150 miles and still failed saying the 2 sensors still had not reset. He called the Chevy House and he said he was told that it will not reset until the temperature was below 78 degrees. Well this time of year in Texas I am lucking if we hit 85 degrees for a low. Is this guy pulling my leg, any truth to this? How do I get my car to pass inspection when I have done everything that has been asked of be besides changing the weather???
I don’t know about the temperature issue, but it sounds like brush off to me (why 78 degrees, anyways? There’s parts of the world where GM sells cars that never get below that). The computer (which is the only thing I can think of that really needs reseting) can be reset with a computer scan tool or by disconnecting the negative battery cable for a while, but I wouldn’t be suprised if there’s something more going on.
I think there’s a communication problem here. The work was done, and CEL off, so the ECM was probably reset to turn off the light. However, the reset also wiped out all the accumulated data from the various sensors, like the O2 sensors, to make the car ‘emissions ready’. Until enough data is stored, the car cannot pass emissions.
Here’s a generic ODB-II drive cycle I found from a technical website. The shop that did the work should be able to help you with the scan tool portion.
This is the process as described in Motor’s OBD II Drive Cycle Guide (the MIL must be off):
Step 1: Connect a scan tool and check monitor status and precondition.
Step 2: Start the engine and let it idle for at least 2 minutes.
Step 3: Drive at 25 mph or more for at least 50 seconds; be sure engine speed remains above 900 rpm.
Step 4: Stop the vehicle and allow the engine to idle for at least 40 seconds.
Step 5: Repeat Steps 2 to 4 ten times.
Step 6: Check the monitor status; it should switch to Complete. If it doesn’t, be sure all enabling criteria are met.
Step 7: If the monitor has not switched to Complete, turn the ignition off and repeat Steps 2 through 5.
Step 8: The readiness status may not switch to Complete if a pending DTC is detected. Perform a second drive cycle to confirm the DTC. Once a second drive cycle is completed, a current DTC will be stored.