2021 GMC Sierra 1500 fuel/propulsion system problems

“My 2021 GMC 1500 Sierra has the 6.2L motor that has significant known issues with catastrophic engine failure involving the camshaft and lifters. The engine in my truck has suffered the same failure but for some reason my VIN is not included in the recall of nearly 600,000 GMC trucks. I called GMC Customer Service and was told bluntly the recall was VIN specific and I would have to bear the 14,000 dollar repair. This is unacceptable since GMC is under federal investigation for knowingly and negligently manufacturing a flawed motor.”

“The vehicle failed to start. It started after 30 minutes and I was able to drive it home. Then it starts and stalls after multiple attempts. Receiving codes P1177 and UI8A2. Was told that a bulletin exists for this issue on GM vehicles, GM Bulletin 24-NA-139, but I found out that it don't cover my VIN number. This can cause the vehicle to stall or shut off while driving. GM should make this bulletin for all vehicles of certain years who carry this modules.”

“1. What component or system failed or malfunctioned, and is it available for inspection upon request? The failure involves the NOx emissions control system, specifically NOx Sensor #2 and the associated NOx catalyst/DPF assembly. Diagnostic trouble codes P11D5, P14D4, P22A1, P2832, P2833, and P28AF confirm abnormal NOx readings caused by sensor breakdown and catalyst performance degradation. Yes, the components are available for inspection at the servicing GM dealership. 2. How was your safety or the safety of others put at risk? A malfunctioning NOx sensor and catalyst can cause the vehicle to enter reduced‑power or limp‑mode operation, which may limit acceleration or speed unexpectedly. This can create hazardous situations during highway merging, passing, towing, or maintaining speed in traffic. Additionally, improper emissions control can lead to engine performance irregularities that may affect vehicle responsiveness. 3. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. The issue has been confirmed by a GM dealership through diagnostic testing. The dealer verified all fault codes and confirmed the NOx sensor…”

“2021 GMC with 6.2L motor. The engine begin to produce a clattering noise in the upper part of the engine. When the clattering happens the vehicle will shudder. I took the vehicle into a certified independent service center who diagnosed a catastrophic engine failure as a result of lifter and camshaft bearing failure. They further advised that this year of vehicle (2021) and engine (6.2L) was known to have this defect and might be subject to a safety recall. I contacted GM customer service who stated that my VIN was not included in the recall even though the year and engine matched the recall. I found that to be odd especially when I noted that nearly 600K vehicles matching my failed engine was recalled. She stated that I (owner) had to bear the cost of replacing the defective engine and labor. I had to have my vehicle transported from [XXX] to [XXX] at the cost of 1400 dollars.”

“1. I am being told that the high-pressure fuel pump (HPFP) catastrophically seized and locked up internally while driving. Because the HPFP on the 3.0L Duramax (LM2) engine is directly driven by the engine's timing system, this sudden mechanical seizure instantly destroyed the engine timing gears and snapped/skipped the timing chain. The failed components are currently intact inside the vehicle and are fully available for inspection upon request at Ron's Smith GMC in Merced, CA. 2. The failure occurred on busy Labor Day (XXX) while our family of [XXX] was traveling back home at 70 mph on a major highway. The truck violently shook, instantly lost all engine power, and forced the vehicle into a dangerous limp-mode state before completely stalling in live highway traffic at night around 10:45 pm. This sudden loss of propulsion at high speed severely compromised our ability to safely navigate out of the way of fast-moving highway traffic, creating an immediate & extreme risk of a high-speed rear-end collision. At times hazard lights didn't work causing family panic & screaming as truck shook with passing traffic. 3. The problem has been officially confirmed by Ron…”

“1. I am being told that the high-pressure fuel pump (HPFP) catastrophically seized and locked up internally while driving. Because the HPFP on the 3.0L Duramax (LM2) engine is directly driven by the engine's timing system, this sudden mechanical seizure instantly destroyed the engine timing gears and snapped/skipped the timing chain. The failed components are currently intact inside the vehicle and are fully available for inspection upon request at Ron’s Smith GMC in Merced, CA. 2. The failure occurred on busy Labor Day (XXX) while our family of [XXX] was traveling back home at 70 mph on a major highway. The truck violently shook, instantly lost all engine power, and forced the vehicle into a dangerous limp-mode state before completely stalling in live highway traffic at night around 10:45 pm. This sudden loss of propulsion at high speed severely compromised our ability to safely navigate out of the way of fast-moving highway traffic, creating an immediate & extreme risk of a high-speed rear-end collision. At times hazard lights didn’t work causing family panic & screaming as truck shook with passing traffic. 3. The problem has been officially confirmed by Ron…”