145 of the
2,284 complaints filed about the GMC Sierra 2500
are about the fuel system —
6% of everything owners reported.
The worst model year for it is 2003.
After finishing a long drive south, I shut the engine off and a yellow engine code popped on. I connected my computer to it and revealed a P129F code (fuel pump control module). I have noticed that other GMC models have been included in a recall concerning this problem. The 2021 GMC 2500 Denali should be also since it is the same problem. This needs to be covered by the manufacturer since it is a constant problem.
NHTSA complaint #11753689 — an unverified report by a vehicle owner.
I am reporting repeated failures involving both the transmission and diesel emissions (DEF) system on my 2021 GMC Sierra 2500HD Denali equipped with the 6.6L Duramax diesel engine and Allison 10-speed automatic transmission. While under warranty, the truck required replacement of the aftertreatment fuel injector and later the Reductant Control Module due to DEF/emissions system failures. General Motors also completed recall-related transmission software updates on the vehicle. At approximately 154,833 miles, the transmission began shifting improperly, set transmission fault codes, and required complete replacement at my expense. Less than 5,000 miles later, the vehicle again experienced a "Service DEF System" warning with multiple diagnostic trouble codes. Repairs required replacement of the DEF tank, DEF heater assembly, and NOx sensor. These repeated failures involve major drivetrain and emissions components on a heavy-duty truck. DEF system failures can place the vehicle into reduced-power (derate) mode, limiting vehicle performance and creating potential safety concerns while driving or towing. I am submitting this complaint so these failures can be documented as part of NHTSA's evaluation of similar vehicles.
NHTSA complaint #11746749 — an unverified report by a vehicle owner.
Filled tank with diesel and truck wouldn’t turn back on. We were next to a jiffy lube and they were able to run a scan and it said there was a broken fuel module. There’s only around 60,000 miles on it, it’s 4 years old, and left my son and I stranded.
NHTSA complaint #11743960 — an unverified report by a vehicle owner.
I recently purchased my vehicle from Big Star Dealership in Baytown Tx. At a little over 1000 miles i was towing a camper. The vehicle stalled, fuel pouring from engine. It was towed and repaired due to fuel pump failure. At a little over 3000 miles the vehicle would not start. Dealership initially said water contamination then changed it and said gasoline contamination and now they say DEF contamination. The vehicle stalling the first time almost caused me to wreck the vehicle
NHTSA complaint #11737988 — an unverified report by a vehicle owner.
GM Duramax L5P diesel engine electrical connector for #4 fuel injector. This failure caused the Diesel exhaust brake, which controls downhill speed, to disengage, extreme shaking of the vehicle, emissions system warning and speed limiting. This occurred while descending a steep grade while towing a 34 feet long, 10,000 pound trailer. This is a known issue with this diesel engine and documented in GM Technical Service Bulletin 23-NA-027. Inspection and repair at a GM dealership confirmed a known issue with the #4 injector pigtail connector caused by improper wire routing and interference wit the Sound Shield and Valve Cover Heat Shield This was a sudden failure of the #4 pigtail connector with no advance warning. In addition to violent shaking of the vehicle, multiple warnings on the DIC indicating that the Diesel Brake was disengaged, the emission system had an issue, and speed would be limited.
NHTSA complaint #11736800 — an unverified report by a vehicle owner.
The vehicle went into low power mode and said to pull over. As soon as that message appeared the next warning appeared and said to shift to neutral and pull over immediately and attempt to restart. The vehicle immediately shut off after second warning before having time to pull over from first message. I was able to pull most of the way off the road as the vehicle had shut off there was no power steering and had limited ability to steer the vehicle. This all happened without advance warning or any other warning that there was an issue while traveling at over 75mph. Vehicle would not restart and needed to be towed. Dealer stated it was a fule control module that was hard to get due to a recall. But that my vehicle was not part of that recall.
NHTSA complaint #11724530 — an unverified report by a vehicle owner.
The contact owned a 2019 GMC Sierra 2500. The contact stated that on several occasions while driving at undisclosed speeds, the vehicle lost motive power. There was no warning light illuminated. The vehicle was restarted; however, the failure recurred. The vehicle was taken to an independent mechanic, where it was diagnosed and determined that the rear fuel tank had failed and needed to be replaced. The vehicle was not repaired. The dealer was contacted. The vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 65,580.
NHTSA complaint #11717761 — an unverified report by a vehicle owner.
Component / System Failure The exhaust system, specifically the exhaust manifolds and previously the EGR system components, appear to have failed or malfunctioned, allowing exhaust gases to enter the passenger cabin. The dealer initially replaced the EGR cooler diverter on December 23, 2025. However, the condition persisted. On February 3, 2026, cracked exhaust manifolds were identified by the dealership, and a major front-end teardown was advised to complete the repair. The vehicle is currently available for inspection upon request. ⸻ How Safety Was Put at Risk The malfunction allowed exhaust gases, including carbon monoxide, to enter the passenger cabin during vehicle operation. Carbon monoxide readings inside the cabin reached up to 50 parts per million (ppm) while driving. Carbon monoxide is a toxic gas that can cause: •Headaches •Dizziness •Impaired concentration •Nausea •Vision disturbances Because carbon monoxide is odorless and colorless, this presents a significant safety risk, particularly at highway speeds where driver alertness is critical. The exposure occurred while operating the vehicle in normal driving conditions. This created a potential risk of driver impairment and increased risk of collision. ⸻ Has the Problem Been Reproduced or Confirmed? Yes. The vehicle was presented to the dealership three times for the same exhaust intrusion concern: •December 16, 2025 •December 29, 2025 •February 3, 2026 During the February 3 visit, the dealership confirmed cracked exhaust manifolds requiring major disassembly for repair. The carbon monoxide readings were observed during vehicle operation. The exhaust odor and intrusion symptoms were consistently present following the first attempted repair. ⸻ Has the Vehicle Been Inspected by Manufacturer or Others? The vehicle has been inspected by the authorized dealership on multiple occasions. Two manufacturer customer care cases were opened.
NHTSA complaint #11717926 — an unverified report by a vehicle owner.
The contact owns a 2024 GMC Sierra 2500. The contact stated that the vehicle was idling roughly, and the RPM fluctuated between 500 and 1,000 RPM while idling. The check engine warning light was illuminated. Additionally, the contact stated that the fuel economy had decreased to 13 miles per gallon. The contact stated that upon scanning the vehicle, the contact retrieved DTC: P0606 and P062B. The contact related the failure to GM Campaign Number: N232415860 (Fuel Injector Flow Rate Compensation). The dealer was contacted and informed the contact that a fee would be charged for a diagnostic test. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 70,000.
NHTSA complaint #11696287 — an unverified report by a vehicle owner.
The contact owns a 2019 GMC Sierra 2500. The contact stated that while her husband was driving 30 MPH and depressing the accelerator pedal, there was an abnormal sound coming from the front of the vehicle, and the vehicle lost power unexpectedly. The contact stated that her husband was able to pull over to the right side of the road while waiting for tow truck assistance. The vehicle was towed to the residence. The vehicle was not towed an independent mechanic or dealer to be diagnosed. The engine was replaced, and the vehicle was repaired. The contact related the failure to NHTSA Campaign Number: 23V047000 (FUEL SYSTEM, DIESEL); however, the VIN was not included in the recall. The manufacturer was not notified of the failure. The failure mileage was 143,000.
NHTSA complaint #11695231 — an unverified report by a vehicle owner.
The contact owns a 2022 GMC Sierra 2500. The contact stated that while driving at an undisclosed speed, the contact heard a clanking sound coming from the steering wheel while attempting to make a turn. There was no warning light illuminated. The contact stated that the steering wheel was loose. The vehicle was taken to the dealer, where it was diagnosed that the steering column had failed and needed to be replaced. The vehicle was repaired; however, the failure reoccurred. The contact stated that while starting the vehicle, the check engine warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed that the fuel pump module had failed and needed to be replaced. The vehicle was repaired. The contact stated that while driving 70 MPH, the vehicle hesitated, with the brake warning light illuminated. The dealer was contacted. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 53,824.
NHTSA complaint #11680925 — an unverified report by a vehicle owner.
The contact owns a 2015 GMC Sierra 2500. The contact stated while driving at an undisclosed speed, the vehicle lost automotive power and stalled. No warning lights was illuminated. The vehicle was taken to an independent mechanic where it was diagnosed that the Fuel Pump Module needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 129,000.
NHTSA complaint #11672477 — an unverified report by a vehicle owner.
The CP4 pump failed while driving causing vehicle to stall. Upon failure, lost power to steering. Luckily we were on an access road for a rest area and not yet on the interstate. This resulted in a 14.5 thousand repair. No prior warning to pump failure. GM has recently settled a class action related to this pumps failure and has never recalled trucks with this pump to avoid failure.
NHTSA complaint #11668022 — an unverified report by a vehicle owner.
My vehicles High Pressure Fuel Pump failed causing the vehicle to shutoff while driving. In addition, due to the engine shutting down while driving, the power steering quit working causing me to not be able to steer the vehicle. Thank you
NHTSA complaint #11666095 — an unverified report by a vehicle owner.
The contact owns a 2024 GMC Sierra 2500. The contact stated that after parking and turning off the vehicle, the vehicle failed to restart. No warning light was illuminated. The vehicle was towed to the dealer for diagnostic testing, but no diagnostic trouble codes were retrieved. The dealer replaced the fuel pump module. No further information was available. The manufacturer was made aware of the failure and advised the contact to file a vehicle safety complaint with the NHTSA Hotline. The failure mileage was approximately 11,000.
NHTSA complaint #11662578 — an unverified report by a vehicle owner.
My 2016 GMC Sierra 2500 with a 6.6-liter Duramax diesel V8 engine suffered a complete engine shutdown—an issue that is both hazardous and expensive to repair. Fortunately, mine failed in a parking lot. No warning lights or symptoms were present. Failure is instantaneous and can occur any time rendering the vehicle inoperable on high-speed highways, Intersections, etc. Failure always leaves vehicle occupants stranded, creating an unsafe and dangerous situation. My vehicle was towed to a GMC dealer. Repair costs could be as high as $15,000. The 6.6-liter Duramax diesel V8 engine is equipped with a Bosch ‘CP4’ high-pressure fuel pump. These pumps are unreasonably fragile and prone to catastrophic failure causing instant contamination of the entire fuel system with metal shavings. General Motors has agreed to pay $35 million to settle with owners following a class action lawsuit that accused the company of installing defective Bosch CP4 high-pressure fuel pumps in certain Chevrolet and GMC pickup models. This action covered only owners in California, Florida, Illinois, Iowa, New York, Pennsylvania, or Texas.
NHTSA complaint #11660921 — an unverified report by a vehicle owner.
Motor stopped dead while driving on a local Interstate Hwy. Was able to negotiate the truck out of traffic without crashing. Not an easy thing to do in speeding rush hour traffic. Had the truck towed to a reputable repair shop and discovered the CP4 fuel pump had failed and shattered throughout the fuel system. Repairs in the amount of $13,520.30 incurred to get the truck back in service. The attached invoice includes $167.87 for other maintenance not related to the CP4 fuel pump repair. This is a known problem and safely hazard. A class action suit settlement is related to the CP4 fuel pump against multiple truck manufacturers. # [XXX] and can be found at [XXX] . Minnesota is not included in the class action and GM will not address my complaint. Why has this KNOWN safety issue not resulted in a recall? INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11658680 — an unverified report by a vehicle owner.
The contact owns a 2020 GMC Sierra 2500. The contact stated that the vehicle was under NHTSA Campaign Number: 24V797000 (Power Train) and the vehicle was repaired. The contact stated that after the recall repair, the transmission started shifting hard. The vehicle was taken to the dealer, and the contact was informed that the transmission module would reprogram and adjust independently. The contact stated that a week later, while driving approximately 45 MPH, the vehicle started to run rough, and the message engine power reduced was displayed. The transmission fault, parking brake system alert, service parking brake, and the check engine warning light illuminated. The vehicle was towed to the dealer, who diagnosed the vehicle and determined that the fuel injector was open, causing high resistance in the connector for cylinder #4. The transmission could not be diagnosed until the injector was repaired. The manufacturer was informed of the failure and opened a case. The failure mileage was 125,000.
NHTSA complaint #11655399 — an unverified report by a vehicle owner.
Replaced the exhaust tail pipe tip past the DPF and warning light came on after miles of driving. Vehicle was locked up and only able to drive 55 Mph and there was a countdown to it dropping even lower. Dangerous to limit speed. This shouldn’t happen anyway with just changing out exhaust tailpipe. Very costly unnecessary repair
NHTSA complaint #11649759 — an unverified report by a vehicle owner.