[nursekdb]

I just had the oxygen sensor replaced on my 98 caravan and need to pass emissions testing. The guy at the garage said I have to drive it 200 miles to reset the computer. A friend tells me there is an easier way that involves a driving sequence. Is this true? and what is the sequence?

 

[XDGT03]

I've never heard of a driving sequence to accelerate the computer reading.

 

[RickMN]

You have to complete a "drive cycle" to get all the readiness monitors to "complete."'

Drive in stop and go traffic with at least 4 idle periods of at least 30 seconds each. Then drive on the highway at a constant speed over 40mph but less than 65 mpg for at least 15 mins. Avoid heavy acceleration, sudden deceleration, and wide open throttle.

 

[donald7150]

just pull the IOD fuse for a few minutes, that should take care of it

 

[Rick99]

just pull the IOD fuse for a few minutes, that should take care of it

This will not help. The computer runs a number of emissions tests called "monitors". Each test runs when certain operating criteria are met. For example, the torque converter clutch monitor will run when the transmission temperature is at the right level, the vehicle is traveling over 45 or so and the throttle is less than 10%. The computer will command lock up and then it will see if the difference between transmission engine rpm and transmission input rpm is within "specs" (in the case of the minivan, less than 60rpm difference). If the test shows that the vehicle is in spec, the computer will record that test as a "pass" in its memory. Then when you go for your emissions check, the technician will check all the test results-- they must all be "pass" for the vehicle to pass emissions.

This prevents someone that has a check engine light on from cheating by simply clearing the light before going in for the emissions test.

The trick for you is to allow the conditions for all of the monitors to run so that the car can pass emissions. What RickMN has written should do the trick.