This Problem Across All Years
I own a 2021 Chevrolet Silverado 2500HD Duramax diesel with approximately 100,300 miles. The truck began displaying a “Service Emissions System” warning and a countdown message that in a certain number of miles the vehicle will be limited in speed (for example to 65 mph). GM’s own Duramax diesel owner’s supplement explains that when a “Service Emission System” message appears it is accompanied by a distance-until-speed-limit countdown and that the truck will progressively limit speed first to about 65 mph and then to about 55 mph if the condition is not corrected, telling the owner to see the dealer. This creates a safety risk because the derate can occur while driving on highways or rural roads, where an unexpected limit on maximum speed can interfere with merging, passing, and keeping up with traffic. This is our only vehicle, and we must use it for important medical appointments, including cardiology and surgery-related visits. The condition started only about 300 miles beyond GM’s 5-year / 100,000-mile powertrain warranty. I opened a case with Chevrolet / GM Corporate (Service Request No. XXX) and took the truck to Sons Chevrolet in Columbus, Georgia on November 17, 2025 for this issue and a rear wheel lockup recall. The dealer kept the truck from about 9:00 a.m. to 3:00 p.m. and indicated they might need to keep it for at least two more days, but I was not given a clear written explanation of the diagnostic trouble codes or a firm repair plan. Because GM’s own manuals describe this “Service Emission System” message together with speed-limit countdowns, and because the vehicle can actively limit speed on the road if the fault is not resolved, I am concerned this represents a broader emissions/derate defect on late-model Silverado HD Duramax trucks. I request that NHTSA review similar complaints and consider whether further investigation or a safety recall is warranted. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
I own a 2021 Chevrolet Silverado 2500HD Duramax diesel with approximately 100,300 miles. The truck began displaying a “Service Emissions System” warning and a countdown message that in a certain number of miles the vehicle will be limited in speed (for example to 65 mph). GM’s own Duramax diesel owner’s supplement explains that when a “Service Emission System” message appears it is accompanied by a distance-until-speed-limit countdown and that the truck will progressively limit speed first to about 65 mph and then to about 55 mph if the condition is not corrected, telling the owner to see the dealer. This creates a safety risk because the derate can occur while driving on highways or rural roads, where an unexpected limit on maximum speed can interfere with merging, passing, and keeping up with traffic. This is our only vehicle, and we must use it for important medical appointments, including cardiology and surgery-related visits. The condition started only about 300 miles beyond GM’s 5-year / 100,000-mile powertrain warranty. I opened a case with Chevrolet / GM Corporate (Service Request No. XXX) and took the truck to Sons Chevrolet in Columbus, Georgia on November 17, 2025 for this issue and a rear wheel lockup recall. The dealer kept the truck from about 9:00 a.m. to 3:00 p.m. and indicated they might need to keep it for at least two more days, but I was not given a clear written explanation of the diagnostic trouble codes or a firm repair plan. Because GM’s own manuals describe this “Service Emission System” message together with speed-limit countdowns, and because the vehicle can actively limit speed on the road if the fault is not resolved, I am concerned this represents a broader emissions/derate defect on late-model Silverado HD Duramax trucks. I request that NHTSA review similar complaints and consider whether further investigation or a safety recall is warranted. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
The contact owns a 2021 Chevrolet Silverado 2500. The contact stated that while slowing down and coming to a stop, the accelerator pedal was depressed while in drive; however, the vehicle started to roll backwards. The contact depressed the brake pedal to prevent the vehicle from rolling backwards, and the RPM became elevated to 5,000 RPM. The contact immediately turned off the vehicle to prevent the RPM from continuing to increase. The vehicle was shifted to park, restarted, and then shifted to drive(D) and the brakes released. While releasing the brake pedal, the failure reoccurred. The vehicle was immediately turned off and towed to the residence. The dealer was informed of the failure of the clutch pack, which was welded together from friction. The dealer scheduled an appointment; however, the vehicle was not diagnosed or repaired. The manufacturer was not informed of the failure. The failure mileage was approximately 100,000.
The contact owns a 2021 Chevrolet Silverado 2500. The contact stated that while slowing down and coming to a stop, the accelerator pedal was depressed while in drive; however, the vehicle started to roll backwards. The contact depressed the brake pedal to prevent the vehicle from rolling backwards, and the RPM became elevated to 5,000 RPM. The contact immediately turned off the vehicle to prevent the RPM from continuing to increase. The vehicle was shifted to park, restarted, and then shifted to drive(D) and the brakes released. While releasing the brake pedal, the failure reoccurred. The vehicle was immediately turned off and towed to the residence. The dealer was informed of the failure of the clutch pack, which was welded together from friction. The dealer scheduled an appointment; however, the vehicle was not diagnosed or repaired. The manufacturer was not informed of the failure. The failure mileage was approximately 100,000.
JULY 2022 DPF filter was throwing check engine light. Took to dealer to get diagnosed, part was ordered and the DPF was replaced August 19th 2022. Started to get headaches in vehicle while driving it. OCT 9th ended up in hospital after driving vehicle and was diagnosed with CARBON MONOXIDE POISONING. Experienced symptoms of losing consciousness, worst headache I've ever had, nausea for 5 hours, loss of feeling in body and seizing of body. Took truck to dealer to get inspected twice and nothing was found to be wrong with it. NOV 10th Took truck on another road trip and was having similar symptoms as before however had more chest pain this time so went back to hospital. Took truck back to dealer to have inspected again and was told that it was fine. Nov 18th took truck on another road trip and within 20 mins of driving had another horrible headache. Pulled over and needed to get air and ended up driving truck 4 hours home with windows and sunroof open to avoid getting carbon monoxide poisoning again. I have been ill since August and that is due to diesel and carbon monoxide poisoning every single time I drive the vehicle which is daily. The truck has been now at the dealership for 70 days without any update or improvement in the case.
JULY 2022 DPF filter was throwing check engine light. Took to dealer to get diagnosed, part was ordered and the DPF was replaced August 19th 2022. Started to get headaches in vehicle while driving it. OCT 9th ended up in hospital after driving vehicle and was diagnosed with CARBON MONOXIDE POISONING. Experienced symptoms of losing consciousness, worst headache I've ever had, nausea for 5 hours, loss of feeling in body and seizing of body. Took truck to dealer to get inspected twice and nothing was found to be wrong with it. NOV 10th Took truck on another road trip and was having similar symptoms as before however had more chest pain this time so went back to hospital. Took truck back to dealer to have inspected again and was told that it was fine. Nov 18th took truck on another road trip and within 20 mins of driving had another horrible headache. Pulled over and needed to get air and ended up driving truck 4 hours home with windows and sunroof open to avoid getting carbon monoxide poisoning again. I have been ill since August and that is due to diesel and carbon monoxide poisoning every single time I drive the vehicle which is daily. The truck has been now at the dealership for 70 days without any update or improvement in the case.
MY TRUCK WILL NOT START RANDOMLY. THE TRUCK WILL CRANK BUT WON'T FIRE. IF I WAIT A WHILE IT WILL EVENTUALLY START. I TOOK IT TO THE DEALER AND WAS TOLD THAT THEY COULD NOT RECREATE IT. NO CHECK ENGINE LIGHT ON AND NO ERROR CODES NOTED.
MY TRUCK WILL NOT START RANDOMLY. THE TRUCK WILL CRANK BUT WON'T FIRE. IF I WAIT A WHILE IT WILL EVENTUALLY START. I TOOK IT TO THE DEALER AND WAS TOLD THAT THEY COULD NOT RECREATE IT. NO CHECK ENGINE LIGHT ON AND NO ERROR CODES NOTED.
6.6L GAS TRUCK WOULD NOT START. FORUMS IVE VISITED STATE THIS IS A KNOWN PROBLEM WITH THE ECM. AFTER APPROX 30MINS IT STARTED. HOWEVER BEFORE THAT IT SPUTTERED OUT EVERY TIME I WOULD TRY TO START IT. IT APPEARS TO BE AN INTERMITTENT PROBLEM. IT RAN FINE ONCE IT EVENTUALLY DID START. ALSO AUTO START WOULDN'T ENGAGE WHEN THIS PROBLEM WAS OCCURRING.
6.6L GAS TRUCK WOULD NOT START. FORUMS IVE VISITED STATE THIS IS A KNOWN PROBLEM WITH THE ECM. AFTER APPROX 30MINS IT STARTED. HOWEVER BEFORE THAT IT SPUTTERED OUT EVERY TIME I WOULD TRY TO START IT. IT APPEARS TO BE AN INTERMITTENT PROBLEM. IT RAN FINE ONCE IT EVENTUALLY DID START. ALSO AUTO START WOULDN'T ENGAGE WHEN THIS PROBLEM WAS OCCURRING.