The contact owns a 2005 GMC Sierra. While driving at approximately 60 mph, the engine suddenly increased in speed to approximately 10 mph. The contact stated that the display panel read "reduced power mode" and the check engine warning light illuminated. The vehicle was restarted, but the failure recurred multiple times. The vehicle was driven to an independent mechanic where it was diagnosed that the throttle body needed to be replaced. The vehicle was repaired; however, the failure recurred without warning. The vehicle was then taken to a dealer where the throttle body wire harness, the throttle accelerator control module, and the accelerator pedal assembly were repaired. The repair failed to remedy the failure. The failure mileage was approximately 270,000.

- Cynthiana, KY, USA

Engine has lose of engine coolant over time with no evidence of leaks found. We brought the truck to a GM dealer which told us this was a known defect issue. They provided us with bulletin # 06-06-01-019B document id 1986750 which clearly state this was defect in the casting of the castech heads. The cost with parts and labor is $3,100 dollars. Clearly, GM should cover this cost since this obviously is a known defect. Searching the internet you can see a large number of people experiencing this issue with little or no help from GM.

- Leeds, MA, USA

Crank vehicle turn corner, message engine power reduced, check engine light appeared, turn around return 200 feet to home, check all fluids connections turn off ignition, unable to start engine, let sit, unable to start engine, drive wife to work other vehicle, recheck all fluids connections, refill coolant, crank engine, coolant discharge on overflow line on cold engine, kill engine would not start, go to autozone get extra coolant and new gas cap. Return coolant level ok. Install new gas cap, engine hard to crank like vapor lock or no fuel to engine. Crank engine, let run, kill engine. Unable to crank, return to work, return in 3 hours, reinstall old gas cap, check fluid levels, ok. Crank engine let run for 5 minutes, check engine light still on, wait one hour, crank engine back to normal check engine light off, engine run ok, drive short test drive. Unable to operate vehicle safely for 6-8 hour period, unsure if vapor lock, bad fuel, fuel filter, bad plugs, coil on plugs, loose plug wire, etc. Never had any engine problems in the past. Only instrument panel cluster failure, and steering click knock that was fixed by dealer. Research problem on internet, it appears this is a throttle position sensor failure that GMC has identified as a safety problem and made a special extended coverage for 2008 to current year vehicles or ten years or 120000 miles. Fromresearch on computer, it appears tens of thousands of comments regarding this loss of power and engine stop. I am older man and reacted with caution and was near my home. Had I been on a busy street or highway a crash or injury would most certainly occurred with this disabled vehicle the cause. I had never imagined this would happen to me nor had I heard of it from any media source or dealer memos. I am hesitant to drive any distance or on certain high traffic roads due to this problem recurring.

- Lafayette, LA, USA

My vehicle was parked in my driveway. I was walking down the driveway and thought the car was being stolen as it was starting. There was no one in the car. The car did start several times on its own so I disconnected the battery cable and had it serviced immediately. How long it had been doing this I do not know. I do know it had not been doing this on the previous day as I walk be there every day at least 2 times.

- East Meredith, NY, USA

Truck was making a "knocking" noise upon start. Took to dealership mechanic and informed, based on the noise and where it's coming from, it's most likely a cracked cylinder and informed this is "common." Really"? will cost thousands to repair... which I don't have. Frustrating to say the least. It has low miles, serviced regularly. If this is "common" why won't GMC step up and take care of it?"

- Irvine, CA, USA

Took vehicle in for new brakes and coolant leak. No complaint about brakes, but complaint about coolant leak. Coolant leak issue is connected to GM tsb 06-06-01-019B and affects castech 706 cylinder heads. The coolant is leaking into the heads because of a known porosity issue. My engine will have to be replaced if the problem is not addressed because of glycol contamination. GM dealer said to just "keep an eye" on it. A second, independent mechanic, did confirm the coolant leak is not external and my engine will fail if the heads are not replaced. This appears to be a known issue with GM for manufacture years 2001-2006 on the vehicles with the 5.3L engine.

- Raleigh, NC, USA

Faulty castech heads are leaking coolant into engine oil. GM is aware that the 5.3L V8 engines have faulty heads, and they refuse to place a recall to fix the problem. It is not right to not stand behind your product. The repair costs are in the $5000 range.

- Mckeesport, PA, USA

Exhaust in passenger compartment. Service man informed me of broken bolts and that I must replace both manifolds before next inspection.

- Stroudsburg, PA, USA