On my wife's '99 Explorer, she just acquired, we had a P0303, #3 cylinder misfire. I found the plug cracked and replaced it. Do the codes reset themselves or do I have to do it? I'd rather not disconnect the battery and reprogram the radio. Thanks.

 

The light will go out soon, after the PCM is able to confirm the misfire is no longer an issue. But, keep in mind that the PCM will store the P0303 code as a history code for quite some time. That's really only an issue if you take the truck to a shop for some possibly related issue in the future, they scan the codes, find a misfire code, and charge you to replace all your spark plugs and wires.

You could also call around to the local parts stores. Often parts stores will have a scan tool that they can use to clear the diagnostic codes without resetting your radio stations, etc. Preferably, start with the store you bought the replacement spark plug from.

-Rod

 

Thanks, that's what I was looking for.

 

It's easier to just pull the single fuse that supplies Keep Alive Memory (KAM) power to the PCM for 10 minutes to reset the PCM. It's usually a small value fuse, 5A or less. See owner's manual.

 

I checked the owners manual and couldn't find a fuse that said that in either fuse panels. Another forum said pull the #11 maxi fuse, under the hood and they only went up to 10. I purchased a scanner and I'll clear the codes from there when it arrives.

 

Try fuse F6 under the hood for the 99 Exploder.

 

My code reader arrived last evening so I erased the code.

 

You would still do well to reset the PCM since that also resets skewed fuel and shift tables back to defaults.