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.