OBDII P402 Catalyst below efficiency (Page 1/1) Hank is Here DEC 27, 09:37 AM I am have been trying to get my pickup inspected (02 Silverado 4.3), the issue has been with the emissions portion of the inspection and not the safety. Due to bad luck the SES light came on right before I dropped it off. I cleared the code but to no avail, it failed since the code was just cleared. I think no problem it is a bad downstream O2 sensor; to be cautious I replaced all four O2 sensors then cleared the code. Over the weekend I drove the truck around (~100 miles) with no SES light showing. Monday I get a call from the shop that the truck failed again because I didn't have enough miles on it and they the computer was still waiting on a determination. I drove the truck normally for another week putting on ~500 miles with no SES light. The shop called back saying that the computer is still waiting on a determination on the code after being cleared and that it will not pass. I am not an OBDII expert by any means. I know that simply resetting the SES light doesn't clear everything from the memory of the computer, however after a week of driving and 500 miles I would have thought that code would be completely cleared from the memory. Does anyone know how long it takes to completely clear the codes from the memory of a computer in a 2002 Silverado 4.3? What are the criteria the computer uses, # of starts, # of miles, time at operating temperature, ect? Right now the shop owner is driving my truck for a few days to try to try to clear the codes buy putting more miles/time of the truck after the codes was reset. My issue is that my inspection is expired (dumb brain fart on my part, who missed registration/inspection accidentally?); I was given a fix-it ticket and five days to get the inspection complete. Without getting the code issue resolved I can't get it inspected, from a proper standpoint I can't drive the truck since the inspection is expired, thus I am in a rock and a hard place. I don't want to get an actual ticket for something that I know I can avoid. I would like to get this resolved correctly and legally without getting a actual ticket issued. Hank is Here DEC 27, 01:23 PM Well the shop called and said the truck is ready. Apparently the owner of the shop drove it home last night and when he came back in today it passed the computer scan. He only lives three miles away from his shop so after I put on 500 miles an additional six miles was all it needed to clear the computer completly and make a determiantion that the code was competly cleared. I really wonder the criteria it takes to completly erase the codes from memory for the code P402. Tstang429 DEC 27, 08:13 PM ITs not mileage but drive cycles. It has to see certain aspects to become cleared. If you did 500 of freeway driving its possible to not clear. If he new the cycles he may have just went through the proper pattern. Monkeyman DEC 28, 03:56 AM The more important question is, did the shop charge you when he drove the truck around? If he did and he's not a close personal friend, I'd say you got f***ed. If you didn't get charged and/or he's a close personal friend you completely trust, it's whatever Tstang said. Raydar DEC 30, 01:31 PM I've had to reset "readiness monitors" on several vehicles. Sometimes it takes a long time. I've driven my 5.3 Silverado for a week, and not had the monitors reset. As Tstang said, it depends on how you drive, as much as how far you drive. Having said that, if you got a code for catalyst efficiency, it will be back. The cat is dying. Our Miata did the same thing. Came up. Cleared. Came back. The last time it came back, it didn't go away. Once I replaced the cat, it was good.