pulling codes

[matt]

Having O2 sensors plugged in or not will never make a drastic difference (except having a CEL or not). Atleast not right away. Their effect is very subtle, but critical. If you are really curious, give me a call tomorrow and I can explain it.

Swap wiring can be an issue effecting O2 sensor operation.

[rede30]

i understand mostly how these buggers work. Where is a good place to start diagnosing no voltage out of the four wires? Is it bad to run the car on the closed loop with a rich mixture?

[matt]

No O2 sensor = open loop all the time.

I didn't mean explain how the sensor works, I mean I can explain how the software uses the data it gets.

Rich is OK, but costing you gas mileage and power. It's not going to hurt anything.