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Discussion Starter #1
It's good to be back. I've been gone awhile making a major move. I've got an issue I hope someone can help me with. I have a 2013 GMC Yukon with a 5.3 and 172K miles. It threw an O2 sensor code so I replaced them all. After about 100 miles the light went off and all was well. Last week the light came back on. It has about 2K miles on it since all were replaced. Same code, different sensor. A guy who works for a used car dealership told me I should have cranked the car with the sensors out to blow the particles out of the exhaust before I put the new sensors in. He said it happens most every time if you don't do that. He suggested pulling them out, cleaning them up, start the engine, rov it up to around 2500 RPMs for a few seconds, then putting the O2 sensors back in. He said it should solve the problem. Has anyone ever heard of this? Any comments will be appreciated.
 

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Yeah that isn’t good advice never listen used car guys. That is literally the stupidest thing I have heard about working on LS motor in last 20yrs lol

What specific code is it throwing?? Also rear O2 ones aft of cats only tell you the cats are bad and don’t change anything fuel wise. Its the fwd O2s that trim fuel. So post the codes you’re getting. Also unless you delete the code they are still in the ECM and the light may come on and off usually takes X amount of ign cycles not miles of it working correctly to clear itself. So again delete codes. You could disconnect the battery that will clear codes as well. If it returns have them read post here

Also a scan tool that will rear sensor data will help see what O2 is actually reading. Scanners like that are $50-100 on amazon shipped to your door.

Id you don’t have a scanner then have codes read and post here. If you have a code reader clear codes then drive list codes here it they retun.
 

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Thanks BO185, I thought it sounded pretty lame too. I'll get my code reader out of storage and get the code again. My buddy read it and it was driver side down stream. When I originally changed them all, the code was driver side upstream. After changing them all, I disconnected the battery for around an hour. That cleared the code but it came back on in about 20 miles. The next day I drove it 600 miles round trip to Tennessee. It went off about halfway and stayed off until this week.

Thanks for your input. I knew I'd get the straight story here.
 

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Thanks BO185, I thought it sounded pretty lame too. I'll get my code reader out of storage and get the code again. My buddy read it and it was driver side down stream. When I originally changed them all, the code was driver side upstream. After changing them all, I disconnected the battery for around an hour. That cleared the code but it came back on in about 20 miles. The next day I drove it 600 miles round trip to Tennessee. It went off about halfway and stayed off until this week.

Thanks for your input. I knew I'd get the straight story here.
Ok downstream one is not that big a deal. So if the down stream one comes back. Swap the downstream ones. If code follows to the other side its a bad O2 warranty it. If it stays on same side that cat is bad, which gm May warranty as they will cover some emission stuff for a while after normal warranty is up.
 

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Discussion Starter #5
Thanks so much. I'll keep you posted.
 
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