pesky p0420
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Senior User
Joined: Nov 2006
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From: Odessa
pesky p0420
Check engine light has been turning on for a few days then it'll turn off for a few days. I took it to get read and the code was p0420. I have replaced all spark plugs and coil packs. Is my cat shot? Why woukd the CEL be turning off and on? This is on a 07 expy. It was misfiring a few months ago that's when I replaced sparks and coil packs.
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Joined: Mar 2001
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No need to replace the coils and plugs again. It could be a number of thinks. Leaking injector, bad cat, etc. I suggest you take it to a shop you trust. Throwing parts at these things are often costly and fail to solve the issue.
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So a quick run down, is your O2 sensor voltage changing quickly or slowly? ECT in the proper range? What is the mileage on this rig? You said a few months ago you replaced plugs and COPs, how long did you run with a down cylinder, is itpossible enough fuel was dumped to damage the the O2? Was the failed COP/Plug on the same side? Remember as no one has pointed out this is a bank one failure so it's just 1/2 of the engine having issues. I would drive it personally if it idles and seems to run fine you just may burn more fuel than you want to.
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Joined: Nov 2006
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From: Odessa
Montecarlo, I have 101k on the odometer. We ran it maybe 50 miles with a down cylinder. How do I check O2 censor voltage? And the ECT range?
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From: Manitoba
If you want to get dirty, go underneath the vehicle and back probe the wires with a multi-meter. While your under there smack your converters and see if they sound like theres a million broken pieces in there, bad news if it is. Or stay clean and plug in a reasonable scan tool to your obd2 port.
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