Rpm's

Is the CEL on?

THe answer I sent to Larry in response to his PM......

CEL = Check Engine Light. This comes on when there is a DTC (Diagnoistic Trouble Code) stored in the PCM. Using this code gives you a starting point when diagnosing a car.

So did this right after you put a A?F gauge on? I'm guessing something happened with the signal the PCM recieves from the oxygen sensor.....is it installed correctly?