How to Reset Error Code?

I've got a CEL due to a P0420 error code. I don't have my own diagnostic reader, and auto parts store pulled the code for me.

I have no performance issues that I can tell (though admittedly I may have inherited a pickup that wasn't in tip top shape). Many P0420 threads say "reset the code and see if it comes back."

That sounds like a good idea. I've been running with the CEL on for about four months now... I still can't detect any change in performance since when I bought it (two months before the CEL light and 0420 code popped up). I'm in the middle of diagnosing it right now. But if there's a way to reset the error log and see if it pops back up that sounds like a great step to add to what I'm doing.

How do you reset the code? People have mentioned using a error code reader, but I don't have one of those. Some people mention disconnecting the battery, but they don't say for how long.

Any specific instruction on how to reset the code? If I find a bad O2 sensor (FSM-recommended checks are happening tomorrow) and replace it I would assume I'd need to reset the code to see if it comes back (thus confirming if a sensor replacement fixed the issue or not).

I just could not find specific code reset instructions in the forum. Suggestions?

 

Remove the negative cable for a couple mins? Ultragauges are cheap little things that can also clear codes.

 

Yep just disconnect battery. Probly 30 seconds should do it. Or a couple minutes to be safe is what I used to do. Keep in mind it'll take a while, maybe couple drive cycles, for it to complete it's thing and possibly bringing the code back. And it's always a good idea to do the same when replacing the sensors too. My guess is gonna be the rear O2 sensor needs replacing of no change in performance. I think I remember reading somewhere that the cat can throw a code only 5% below optimal efficiency. But a lot of times it's just the sensor itself. They do go bad.

 

Or an obd2 Bluetooth dongle with the Android app 'Torque' . basically what I got mine for, for checking codes. But has lots more useful stuff. Not quite as good as ultragauges tho.

 

Right on! Thanks for the tips! I had a Subaru that required hours of disconnect, which was a pain. If it's just a few minutes or less no problem! I was not familiar with Ultragauge. I'll definitely look in to that further - sounds cool!

 

Disconnecting the battery will reset the code, but don't get excited if it doesn't come back on right away. Usually takes a hundred or two miles for the computer to detect the issue again, sometimes sooner sometimes later. I reset my P0171 code a few times by disconnecting the battery and it always came back within a tank of gas (275 miles or so) until I got the issue fixed.

 

Duly noted. I think the P0420 is going to be a long term fix anyway There is no cheap fix as far as I can tell, so I'm going to be putting a LOT of time into investigation and diagnostics. It's been going on for months, so if it takes a week or two for the code to reappear that's a drop in the bucket. Thanks!