Pontiac Repair: 00 Pontiac Sunfire, pontiac sunfire, p0420 code

Question
Approx. 1 year ago I installed a Walker Direct Fit catalytic converter on my girlfriend's 2000 Sunfire (2.2 w/AT)because there was an exhaust leak at the flex part of the front pipe (mileage was 106,910). 8 months later the check engine light came on w/ a P0420 code (mileage @ 110,510). I installed a new   downstream O2 sensor (aftermarket Standard) and cleared the codes. In approx. 400 miles of driving, the light came back on w/ P0420 and also P0141. I cleared the codes again and drove the car 200 miles. She failed NJ State Inspection because the OBDII system was not ready. There are 3 monitors not ready (Catalytic Converter, Evap. system and heated Oxygen Sensor)and the car will not pass inspection. After several attempts to restore the drive cycles, the same three monitors are not ready. Any suggestions are greatly appreciated. Thank you.(current mileage at 111,042)

Answer
Hi Al:

well first off aftermarket emission parts do not match O.E.M. in quality and that is part of your issue here. the p0410/420 are cat converter ineffeciency codes so that converter you put on is not cleaning the exahaust up correctly. the 141 is an o2 heater code I think and again aftermarket parts do not cut it. putting an os sensor in for a cat converter code will not fix the issue here. It'[s expensive but I suggest you get a GM post converter os sensor and try to get the corredct converter for the car. maybe a junk yard will sell you one. here in NY they will sell them but some states you can't get a used on from a junk yard. look on E-bay as well. as for the monitors not running if you didn't drive it long enough at the correct speeds it didn't have enough of a cool down between drive cycles it will not run the tests. If there is too much or to little fuel in the gast tank it will not run the evap test. the tank has to be between 85% and 15% to run that test. Good luck :)


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a drive cycle is from a cold start to cruising spped of about 35 -40 mph for a few miles and then in the same cycle between 50-60 MPH for another 5-6 miles no stopping during the cruising speeds and it should run some of the tests. a complet cool down and drive it a second time and it should run the tests uaually about 50 miles of mixed loop driving will run the tests the key it the constant speed no stopping and going.. Do NOT beat on it drive it at a gradual pace.. The other issue here could be that the engine computer has already seen the issue with the converter and it's ready to trip the service engine light on again If so it will not run the cat or O2 tests.. Every car has a different drive cycle parameter to run the tests I just gave you a thub nail.. good luck :)