Engine Exhaust System Problems of GMC Yukon

I purchased a magnaflow aftermarket catalytic converter system for my 2008 GMC Yukon slt 5. 3l through walmart’s online marketplace, sold by a third-party vendor called ourdealsrock. The product was advertised as “50-state legal” and compatible with vehicles registered in new york state. However, shortly after installation, my check engine light turned on, and diagnostic codes p0420 and p0430 (catalyst system efficiency below threshold) appeared. Initially, I thought this was a minor sensor issue, but over time, the vehicle’s performance gradually deteriorated. I noticed reduced acceleration, poor fuel economy, and eventually significant loss of power. The vehicle began shaking under load, misfiring, and overheating. These symptoms worsened steadily—not immediately—but progressively after continued driving with the aftermarket converter installed. I had the vehicle inspected by a certified mechanic, who confirmed that the magnaflow converter was not carb-compliant, was not approved for use in new york, and that it had been illegally marketed as such. He also informed me that prolonged use of a non-compliant, malfunctioning converter caused excessive backpressure, leading to complete engine failure over time. The diagnosis was confirmed by a second mechanic before I committed to the engine replacement. The product was later removed from walmart’s site, becoming unavailable for sale in my zip code [xxx] ) shortly after my initial complaint. This shows clear acknowledgment that it should never have been sold to a new york consumer in the first place. But by the time it was taken down, the damage had already been done. Component/system that failed: •magnaflow aftermarket catalytic converter system •ultimately caused failure of the vehicle’s engine block safety concerns: •my family and I were unknowingly driving with a damaged and failing engine •the vehicle’s degraded performance, overheating, and power loss could have compromised our safety during highway d information redacted pursuant to the freedom of inform.

See all problems of the 2008 GMC Yukon 🔎.

Exhaust leak bolt broken passenger side.

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Exhaust leak. Bolt broken on driver side.

While driving today at a speed of 55 mph in somewhat heavy traffic my service traction control and stabilitrack indicator came on as well as a message on the dash saying the same. At which time my vehicle came to slow down and I lost power. I pulled over and and shut the car down and upon restart noticed that not only did white smoke come from my exhaust but the car had a rough idle the same indicators were still on and the engine light had now come on as well and was flashing. I was able to make it home with a rough limp however when I came to a stop felt as though the car was hesitant to keep running or take off. When applying gas there was a thump from the rear wheels like the transmission was not sure how to engage.

See all problems of the 2007 GMC Yukon 🔎.

Broken exhaust bolts on gm engines. This is a well known defect and failure on these engines and is part of the vehicle emissions systems. This is also a very serious safety defect, possible issues with this failure include; carbon monoxide poisoning and engine compartment fire.

See all problems of the 2004 GMC Yukon 🔎.

1999 to present 4. 8,5. 3 5. 7,6. 0 liter engines from gm have inferior grade metal in the exhaust manifold bolts causing them to break. The vehicles will have exhaust leaks and false readings to the oxygen sensors. The exhaust leaks of raw exhaust gases in to the atmosphere translate to extra pollution into the atmosphere from all these vehicles . The other matter is that the computer on the vehicles isn't given the correct oxygen sensor reading because of the leaks ,either gas leaking out or air being drawn into the exhaust stream causing the premature failing of catalytic converters. The computer on the vehicles may or may not warm the customers with a light based on the severity of the exhaust stream leak gm put out replacement bolts for this problem ,but that only fixes the people's that have the time and or resources to visit the gm dealers. All the rest of the vehicles and their owners are responsible for getting the old bolts drilled out and trying to get the vehicles fixed on their own. Lots of pollution taking place and money being spent on a problem that could have been avoided with some proper grade fasteners. And this is on about 12,000,000 cars trucks and suvs. This is being written from someone who has had 25+ cars and has an automotive engineering background. And someone who spent money and precious time on this issue and really should not have had to.

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2 bolts holding the manifold to the 6 l engine of my Yukon denali 2005 are broken. There is consequently gas emission leak at the source, not complying to resource emission laws, potential damage to the catalysor. At the garage, extended warranty refused to cover the bolt and work (but the manifold is) one of the bolt can not be drilled by the outside (no space) and has to be remove by removing the head cover. I am looking at a 10 hours estimate of labor.

The manifold bolts are broken on my 2003 GMC Yukon xl. . Read more...

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Exhaust manifold bolt heads are breaking on my 2005 Yukon xl denali causing an exhaust leak, as well as engine error lights. GMC has denied knowledge of an issue, even though the problem seems wide spread. The bolts need to be removed and replaced. Very expensive repair.

While driving, the steering wheel jerked away from the consumer without warning. The problem was due to the (evo) exhaust valve opening.

See all problems of the 1999 GMC Yukon 🔎.

While driving the consumer heard noise. Dealer indicated it was coming from the exhaust system.

2002 Yukon - brief engine knock when vehilce is started. Also, has an exhaust noise/rattle at approximately 40-42 mph, 1000=1300 rpms. Noises started at approximately 2000 miles.

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My vehicle was serviced by this facility. I am the second owner and have owned this vehicle for less than 1 year. The orig. Owner purchases all vehicles from them for his construction company and maintains them regularly, as I have. I had the part and was told this was not thee problem. This vehicle had a 60,000 mile service brakes and new tires when I bought it. They charged me $1400 and 11 hrs. Labor for these repairs that should take no longer than 3. I am a single mom who was assured they would only fix the things required by gm dealer and I could get minor things done at my regular mechanic. Now they want me to come back and spend another $800. 00 dollars on the air conditioner. I will ask for a full refund or at least half my money back for bad faith and fraudulous activity on the part of a servicing business. I'm a single mom living paycheck to paycheck and they took full advantage of me. Please make sure that I and other innocent trusting people don't get taken by this particular truck center ever again. I f you would like to see a copy of my receipt I would be more than happy to provide that to you. I have paid the $1400 and do not have the additional $1000 they want to complete the repair they say I need. I realize this vehicle is superior but that's why I spent the extra money and serviced it regularly because I thought I was paying for a quality car. The warranty they say is no longer valid. Help!! I will also be contactinf my local consumer advocat as ell as the media. Thank you for your time! sincerely, shannon thompson (state farm insurance company c a. Lic. #0d54268 ) no referrals from me or my CO-workers that's for sure.

Since date of purchase consumer has had an exhaust system problem, causing vehicle to make loud noises. Please provide further details.

Consumer noticed a noise coming from right rear of vehicle intermittently. Dealer was contacted, and changed the exhaust system. Noise stopped for a while, but returned.