definitely annoying
Crashes / Fires:
0 / 2
Injuries / Deaths:
0 / 0
Average Mileage:
39,800 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2012 GMC Sierra engine problems

engine problem

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2012 GMC Sierra Owner Comments

problem #5

Jun 272014

Sierra 4WD 8-cyl

  • 140,000 miles


The fuel injection pump CP4 had a catastrophic failure as I was driving on a heavily traveled four lane highway, us rt.20. I lost power steering and brakes. I felt fortunate that I was not towing a 16,000 lb. Fifth wheel camper down a mountain road.I say this because it was extremely difficult to maintain control over the truck steering it and bringing it to a controlled stop. I have read about these pumps failing on numerous diesel Ford and GM trucks. I also feel if a woman or small person had this happen to them the outcome could end in loss of control resulting in injuries even deaths. The only one that knows the actual number of pumps that have failed is the manufacturers, who will not share that information willingly.

- Medina, NY, USA

problem #4

Aug 152014

Sierra 4WD 8-cyl

  • 35,000 miles
Engine will increase idle from 700 to 900 at any time. One can be sitting at a traffic light and it might increase or decrease. I pull a 5th wheel (35 feet) and it is very difficult to stop with the engine trying to keep going. Also it is very scary to stop on slippery roads. This did not start until the vehicle had approx. 35,000 miles on it. The dealer tells me it is normal, but I have talked to owners of the GM diesel from model year 2008 through 2015 and none of them have this condition.

- Perry, MI, USA

problem #3

Jul 032013

Sierra 8-cyl

  • 2,000 miles
While the vehicle was being driven, it just went dead, no engine, no electric, no nothing. The vehicle was left in place and at some point, caught fire and burned. A total loss. To date, the insurance company has not paid me for my loss but rather has gone to great lengths to investigate me personally, looking for any reason to not pay. So, I've been making two vehicle payments for the last 8 months. As a result, I am struggling financially.

- Olathe, KS, USA

problem #2

Jan 022013


  • 10,000 miles
Apparently GM uses peanut oil to lubricate wiring so they can more easily insulate, etc (accorging to the GM dealer). This attracts rats and mice which chew up the wiring - potentially impacting sensors and other items controlling cruise, stability/traction control, and any number of electrical systems that the driver may be relying upon for safety. I actually had map sensor wires chewed up that disabled my stability/traction systems and inhibited engine performance. Luckily for me it happened in my driveway rather than on the highway. Dealer claims it is not warranty item even though caused by a process that GM elects to use in building the vehicle. This could impact any/every vehicle that GM builds with use of peanut oil (may indeed be all of their models).

- Santa Clarita, CA, USA

problem #1

Oct 172012


  • 12,000 miles
Vehicle was taken to GMC dealer for headlight defect and we were informed that they would have to order parts. Drove truck back to site and while truck was running but stationary smoke was observed coming from the engine compartment. When the hood was raised the entire truck became engulfed and completely burned.

- Beckley, WV, USA

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