The reason they asked if you had gotten bad gasoline or if it had been running rough was to pick your brain for possible reasons the oxygen sensor itself might be going bad. Or telling the computer to set a fault code. Bad gasoline will cause the engine to run less efficiently, and the oxygen sensor might complain about that. Doesn't mean the oxygen sensor is bad, but it might set a code anyway.
From what you've described, it doesn't sound like the oxygen sensor itself is going bad, or that it is complaining about some fuel trim parameter that is out of range. There are other fault codes that would pop up if that were the case. So you car sounds like it's functionally in good shape.
It sounds like the car's computer wasn't able to verify that the heating element that is around the oxygen sensor is working correctly. It's either gone bad, (in which case you'll need a new oxygen sensor because they are both contained in the same unit) or the connection between it and the computer has become compromised.
The oxygen sensor unit tends towards sensitivity and fragility. Partly because of it's environment. High heat namely, and the substance it needs to monitor constantly. Oxygen sensors never last the entire life of a vehicle. I hope this helps.
Tuesday, February 6th, 2007 AT 9:08 PM