okay so I am getting a code on my 92 ls for heated o2 sensor. I swapped the sensor with a known good one and the code was still there. so I put the car on the lift and checked for voltage at the o2 plug on the harness side and there is no voltage. I looked up the wiring diagram on chilton and alldata and it shows that the heater circuit is in the main relay. I swapped the relay out with one from my other 92 and the code is still there. I have not been able to get it back on the lift to check the voltage again with the new relay but I will be able to today. I am just trying to find out if anyone else has had this problem and if so can you point me in the right direction.
The power for heated 02 sensor is supplied by the PGM-FI Main Relay, [fuel injector relay], if engine runs or if there is power at the injectors then the PGM-FI Main Relays fuel injector relay is working and it is not the problem.
If you stilldo not havepower at the 02 sensor, the problemis a break in the connection between injector relays output, [12V+] and the 02 sensor. 94
[QUOTE=fcm;2202971]The power for heated 02 sensor is supplied by the PGM-FI Main Relay, [fuel injector relay], if engine runs or if there is power at the injectors then the PGM-FI Main Relays fuel injector relay is working and it is not the problem.
If you stilldo not havepower at the 02 sensor, the problemis a break in the connection between injector relays output, [12V+] and the 02 sensor. 94[/QUOTE]
well said…
I have voltage at the harness plug now that I changed the relay. but the code was still there. I followed the steps in alldata for the code 41 and I checked the resistance in the o2 sensor heater circuit and it said there should be between 10 and 40 ohms. I had 4 ohms in the o2 so I added two 10 ohm resistors in series with the heater circuit and measured the resistance again and now I am at 24 ohms (within spec) but the code is still there. my only guess is that there is a bad connection at the plug itself. any thoughts