Jump to content
  • Sign up for FREE! Become a GM-Trucks.com Member Today!

    In 20 seconds you can become part of the worlds largest and oldest community discussing General Motors, Chevrolet and GMC branded pickups, crossovers, and SUVs. From buying research to owner support, join 1.5 MILLION GM Truck Enthusiasts every month who use GM-Trucks.com as a daily part of their ownership experience. 

Recommended Posts

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

Edited by KNJ
Added mileage

Share this post

Link to post
Share on other sites

Before you have anything else fixed, fill it up a couple of times with the best top tier premium gas you can find. My Sierra did the same thing at 98K miles. I got the P0420 code. My dealer said that the converters needed to be replaced for $1,600. I read an article that said sometimes the catalytic converter gets fouled if you buy cheap gas. I bought cheap gas all the time. The article said that good premium gas can sometimes clean up the converter and the codes will go away. It worked for me and I only spent an extra $8 per tank on the premium gas. It doesn't cost much to try. 

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Similar Content

    • By Brenden
      Hey Everyone, I’ve been looking at this forum for a long time but I’m a new member. I have a 2015 GMC All-Terrain that I’m wanting to level. I’ve been trying to decide between the ready lift 2.25” with the 2” rear block or Rough Country 2.5” with the 2” rear block. I want to run 275/65r20 tires on the stock wheels. I was also considering buying a set of Hellwig helper springs, I pull a trailer a few times a month and don’t want much to any squat. So I guess my questions are:
      1. Has anyone done either of those kits with that size of tire? (Please share a picture) 
      2. Would it be better to do an Add-A-Leaf
      in place of the 2” block and Hellwigs? 
      I have looked through all the leveling kit post and haven’t really found what I was looking for yet. 
    • By Dgs000
      2007 Silverado 5.3 V8 with AFM with 180,000 miles
      Truck had lifter ticking sound and white smoke upon every start up which would go away after a few minutes, no check engine light
      Replacement list :
      - headgasket
      - valve gaskets
      - upgraded drivers side valve cover
      - valve stem seals
      - intake manifold gasket
      - exhaust manifold gasket
      - 8 new afm lifters
      - 8 new non-afm lifters
      - head gasket bolts
      - engine coolant temperature sensor
      - spark plugs
      - spark plug wires
      - fuel injectors
      - water pump
      - thermostat
      - cam sensor
      - crank sensor
      After completion of engine reassembly no longer had white smoke upon start up and no ticking sound but flashing check engine light code p0300.
      Code p0300 was for cylinder #1, #4, & #7
      Moved coil packs between cylinder #1 and #2 to see if coil packs was bad but no change. Set engine at TDC before installing the rocker arms. 
      All bolts have been properly torque and no parts have been left unplugged or uninstall.
      Any possible advice would be helpful 
    • By jeffvleet26
      hey all, I have a 2015 chev Silverado 1500 with 56k on it. yesterday (5-22-2020). I was sitting in line in drive and started hearing a loud squeal. thought it was the car in front me until I shifted into park and took my foot off the break and it went away! car moved up so I shifted back into drive and moved forward and it did it again just sitting still until I put it back into park. having lots of problems trying to diagnose it. drove it again today (5-23-2020) and it did it again but not as loud. would could this be? checked the tranny fluid and it was in the normal range. any help is great as I travel for work. thanks
    • By Ramblin Man
      Last summer I purchased a 2001 Yukon XL with the 5.3L engine, replaced the rear rotor/pads and air filter, then went on a 13,000 mile 8-month road trip starting in Boston, going through Maine, Atlantic Canada, back to Boston for a seasonable job, then to New Mexico via South, back again to Boston through the midwest and finally Florida to help my folks through covid (all safe). 
      The truck now has 191K miles, but the original title indicated the mileage was not accurate (which is how I got it for  $1,200 on eBay), so, who knows.   The mechanic who did the rear brakes was surprised how little rust was in the undercarriage.  I removed the rear seats, added a mattress and three milkcrates for my stuff, installed a cheap aftermarket radio with bluetooth and a rearview mirror camera.  Brake and ABS warning lights were skillfully covered with duct tape by the previous owner, I removed the ABS fuse because ABS kicked in without need when breaking at low speeds (dirty sensors?).
      Over the 13K miles  I had 2 oil changes + tire rotation at Wally, and poured  Bar’s Leaks into the radiator to stop a slow coolant leak out of the intake manifold.
      I drove full tanks at different speeds on cruise and averaged:
       - ~13 MPG city
       - 20.44 MPG at 55  highway (sorry truckers, thanks for not throwing your pee bottles on my windshield)
       - 19.53 MPG at 60  highway
       - 18.81 MPG at 65  highway

      It’s been a hell of a truck, and now in Florida I have a garage + time, and will do some maintenance.  Here is my list, I appreciate any suggestions (or requests):
      driver side rear caliper/pads/hose (the wheel is a little warmer than the others after driving, and it just started to whistle though pads/rotors are only 13K miles) front rotors and pads, total brake fluid flush check if front hubs need replacement (I occasionally hear a noise when turning left at very low speeds) oil change w/ amazon synthetic  + mobil 1 filter trans fluid flush w/ Dexron VI, new filter, and tighten valve body bolts (sometimes tranny thumps from a stop after highway driving, but the fluid is still pink enough) spark plugs and wires (just tested resistance, 7 AC Delco wires are perfect, at about 660 ohms but the 1 shorter Denso wire is at 505 ohms; double platinum AC Delco 41-962s have some gray and orange and could probably go back, but I’ll change just because I went through the trauma of removing them - BTW, three out of the eight plugs have oil in the threads, should I be happy?) fan clutch (not a lot of resistance, and my ac belt “jackhammers” when moving from idle - which according to some of the forums might be due to higher freon temps at idle due to a dying fan clutch) fuel filter clean and seal all grounds both downstream oz sensors (voltage is getting lazy)  
      I’m predicting that between the freed caliper, new plugs/wires, fuel filter, trans fluid  and oz sensors I will see some mpg improvement over the next 10K miles, which will hopefully cover the Pacific Southwest, California and Pacific Canada.  Thank you all for sharing you knowledge here, I look forward to putting it all into practice.

    • By JimmyKo
      Have any of you been able to get GM to cover radiator leaks beyond the b2b warranty? I have 40k on mine and was just informed I have a leak. I noticed they extended the warranty on 14 and 15’s but I’m not seeing any newer models being covered. 
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Forum Statistics

    Total Topics
    Total Posts
  • Member Statistics

    Total Members
    Most Online
    Mallery O'Hara
    Newest Member
    Mallery O'Hara
  • Who's Online   42 Members, 0 Anonymous, 1,790 Guests (See full list)

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.