Purchased from an auction a '97 deville. originally coming from Canada, entering the US in 2000. NY has now new vehicle emission laws for '96 and newer vehicles. This vehicle has failed this new testing since March of '05. When the NYS computer is plugged into the connector under the dash it has 3 monitors saying "NOT READY" O2 SENSOR, HEATED O2 SENSOR AND CATALIST SENSOR. (ALL NOT READY). This car has has numerous drive cycles that were performed. A new computer PCM was also replaced, following more drive cycles. still no luck. The sensors are good I was told. They do show values when plugged into a computer while running. This work was performed at a certified GM dealership. The car has 116k for mileage.
Its in beatiful shape and was cared for. The dealership has said to me they have never seen this before. ANY HELP????? Thankyou

 

ask some who is knowledgeable on it and get a cross count on the O2 sensor if its between 1-4 I would replace it if its 10 or more I would say its ok.

I had a bad O2 and my injectors where not all firing and some where stayed open and keep fouling the o2 sensor.


Start from the begging check for vacuum leaks and check eng codes again.