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P0420 (catalyst efficiency below threshold) code keeps coming back!
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By Bigpapa
I have a 2014 GMC 1500 with a 5.3L. I recently replaced my CATs because I was getting the dreaded P0430 code. SO I put new Magnaflow exhaust systems as well as brand new sensors in it. I got it all in and about a day after I got it all installed I got the same code P04030. I double checked the seals and sensors and looked at the live data and it all looks on the level...the only other thing I can think is that there is a wiring issue with it...the connector on bank 2 sensor 2 looks in order so I'm a little confused as to why I'm still getting this code other than there is a ground or an electrical issue I haven't looked at.
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By KNJ
Hi! In April, my Yukon was throwing codes P0172 P0175. Local GMC dealer in Louisiana "fixed", by replacing some sensor. Traveled to PA, codes came back on. Local GMC dealer fixed by replacing BCM, body control module in June. Now my check engine light is back on! Power train Warranty ran out 2-3 weeks ago. Also had extended warranty, which also ran out at 5 years, which was Sept. Code onstar says its throwing now is P0430, all of the codes from I can find are related to exhaust system. My question is are these 3 codes related??? Could this be something they will have to fix under warranty, given it's related and has been worked on several times?
If not, what does this mean? Catalytic converter bad? Help! My husband is being laid off in the next week. So, obviously finances are tight. Yes, obviously itll be fixed regardless, just trying to plan and cut back elsewhere if needed. This has been a great vehicle! As luck has it, trouble starts when warranty runs out.
Really wanting to trade, but waiting on new body
Adding mileage if matters, 91K
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By Blakehyates
Hello,
I went to go crank my truck and it started but sounded horrible. The whole truck started shaking and the rpm's were dropping and the fuel gauge was twitching. I drove a mile down the road to the GM dealership and on the way the check engine light was flashing. The tech read the code and it came back as P0137 which I believe is an O2 sensor. Would a sensor cause my truck to die?
2015 Silverado 1500 LTZ 77k miles.
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By Coop8202
I have a 2008 GMC Sierra with the 5.3 liter engine. I hear a rattle coming from the underneath of the truck only at 1000-1500 RPM’s. I checked for loose clips and stuff but I have found nothing. It doenst affect the way the truck runs just the sound. Also, the temperature doesn’t affect the rattle.
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By erockwell
I don’t know if you all remember me or not. About a month ago I posted about my Yukon misfiring terribly. I fixed that thanks to your expertise and now I have a couple other small issues.
Number 1. I keep getting a P0430 code. I’m pretty sure the right side cat is bad. When reading the O2 sensors. The graph shows identical readings for the upstream and downstream sensors. I’m pretty much resigned to the idea that I’ll have to replace the cats, and found a new set for a decent price. Still I was wondering if any of you could recommend a good set. I can’t weld, so I’ll need to buy the whole assembly. I (think I) have some time on this because I don’t need another emissions test for over a year, but correct me if I’m wrong and if this problem is actually more urgent than I think it is.
Second, and more importantly, I’ve got a squeaky wheel. I tried to diagnose it, by jacking each wheel off the ground and turning it manually, but nothing happened. I checked the CV joints and brake pads in the front, but after a really bad experience when I was younger I won’t mess with drum brakes, so I don’t know if something is up with one of the rear drums, and the rear axle doesn’t have CV joints. The noise seems to come from the front driver’s side wheel. So, if the CV joints and brakes seem fine does that mean the bearings are going bad? Is replacing them possible without an impact wrench and a hydraulic press? Could I just pack them and hope for the best? I’m going to do a little more trouble shooting and update the thread with any new pertinent info.
Thanks,
Eric
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