CEL is ON...removed 7.5 amp clock fuse...CEL is still on

**jasonthe** · 06-25-2012, 19:57

My CEL is ON so I removed the 7.5 amp clock fuse to reset. When I started the car, the CEL came back on immediately (note: not comes back on after driving for a bit.).

So I remove the fuse this time "permanently" and start the car and the CEL is still on, clock isn't working and radio is reset.

Other info: code is 42. (possible reason for the CEL staying on?)

WHY DOESN'T THE MEMORY OF THE CODE RESET?

**pingu81** · 06-25-2012, 20:32

Perhaps you have an issue with your car? ...just maybe?

**pgilliam1** · 06-25-2012, 21:25

I'm going to assume your car is a OBDI (1991 to 1994). Code 42 is for the rear primary O2 sensor heater circuit (bank 1 sensor 1), PN:234-4096 @ oxygensensors.com).
Let's go through the steps for resetting the ECU:
- get engine to operating temp
- turn the car off
- take out the clock fuse for 15 minutes
- put the fuse back in
- turn the engine on and let idle for 15 minutes or until the engine idles smoothly at low RPM's (do not interfere by giving it gas - let it idle). You should hear the engine increase and decrease rpm while it is learning.
- turn the ignition off, then immediately turn the ignition back on (this stores the new settings).
- you're done
If the car is running OK chances are you can replace the O2 sensor and be done with it. Good Luck.

**jasonthe** · 06-26-2012, 12:28

My ecu will not reset when i remove the clock fuse. My CEL stays on.

Will removing the battery cable reset the CEL?

I have a 91, 5 speed.

**docjohn** · 06-26-2012, 16:51

Originally Posted by jasonthe

My ecu will not reset when i remove the clock fuse. My CEL stays on.

Will removing the battery cable reset the CEL?

I have a 91, 5 speed.

did you read post #3?

**jasonthe** · 06-26-2012, 17:31

yes I read post 3 and tried that.

LarryB told me that the first thing the ecu checks for is the 02 sensor so that is why the cel comes on as immediately even without driving.

Going to replace my 02 sensor and i will post if the cel goes away.

**SuperSonic** · 06-27-2012, 01:15

Battery will work. I used to pull the battery cable when I reset my light. Then I would press the brake three times to drain what I thought was the remaining battery. It worked for me to reset the light.