2021 GMC Sierra 1500: hesitation when accelerating

Filed Oct 30, 2026 · Engine, Steering · 34,000 miles · AK

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 45 MPH, there was an abnormal knocking sound coming from the vehicle. The vehicle started hesitating, and there was a loss of power that became worse over time. Additionally, the “Service Engine” and “Power Train” warning lights were illuminated. The messages “Loss of Steering Assist - Be Alert” and “Service Parking Brake” were displayed. The following day, the vehicle was driven in LIMP Mode to the dealer and was diagnosed with engine failure. The contact stated that there was an ongoing the federal safety agency investigation associated with the 6.2L engines. The failure mileage was approximately 34,000.

Filed Oct 18, 2026 · Brakes, Engine · LA

Service light came on because the brake petal would push back when I tried to start it. At times, I had to push down all the way almost to the floor and then it would start. If I eased up slightly or did not push all the way, the truck would hesitate to start. I brought it in to Courtesy GMC of [XXX]. They found metal debris in oil. The car warranty did not want to replace the entire engine as General Motors' bulletin had stated as a corrective solution. They only wanted to replace the camshaft and rocker arms because [XXX] did not tear down the engine to the point of failure. [XXX] stated that they did. After going back and forth with EasyCare (myself and [XXX]) I authorized the repairs EasyCare suggested. XXX, a Service Brake Assist message came on. I brought it to [XXX]. They rectified the issue. XXX,Truck stalled getting off XXX at light. Truck kept turning on and off. I put it in park and was able to turn in on. As I was driving the truck was rocking back and forth as I pressed the gas pedal. I was able to pull into the Super1 Foods parking lot. Trucked stalled halfway into parking lot. After two attempts to turn off and start truck I was able to pull it up all the way to ensure safety. Texted [XXX] at Courtesy. I called the number he sent and a tow truck from Cliff’s Towing and Recovery, LLC retrieved my truck and brought it to Courtesy GMC in [XXX] where it is currently residing. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 28, 2026 · Engine · MI

I had the L87 recall completed, and the vehicle passed inspection. The dealership completed the required protocol and replaced the engine oil with 0W-40. Approximately 6,000 miles later, while traveling at about 75 mph and six hours from home, I experienced a brief loss of power followed by an immediate return of power. My wife and I noticed it but, with no warning lights or alerts, continued driving while monitoring the vehicle. About 10 miles later, we began hearing a faint squealing noise that progressively became worse. I was able to exit the highway safely, but once I came to a complete stop, the engine shut off and would not restart. I had the vehicle towed to the nearest dealership, where it was determined that I had suffered a catastrophic engine failure. No loaner vehicle was available, leaving my family stranded six hours from home with an inoperable vehicle. It took approximately seven to eight weeks for the repair to be completed. When I received the vehicle back, I immediately noticed something still was not right. At around 40 mph and 1,000 RPM, the truck would shudder or hesitate. My local dealership diagnosed a poor spark plug connection on cylinder #3, which was causing arcing and a misfire. After the connection was repaired, the issue was resolved. My local dealership is currently working with the repairing dealership to address several minor workmanship issues, including wire clips, fittings, and missing bolts. This entire event was unexpected. There were no warning lights, alerts, or unusual noises before the initial loss of power. The only indication of a problem was the sudden power loss followed shortly thereafter by a horrific screeching noise. Thankfully, I was able to safely exit the highway and bring the vehicle to a stop. Considering I was traveling at 75 mph, the situation could have been much worse.

Filed May 26, 2026 · Transmission · TX

The truck has a studder that comes from the transmission when at highway speeds. the studder can be felt at random intervals (seconds) from all passengers. The studder is also present on starting up a slope or accelerating from a stop at a slow pace. when accelerating slowly the jerk is more prominent. We have taken it to the GM Dealership, they confirmed the issue was present. The dealership said the GM guidence was to 1st try a re-program and then replace the torque converter. The program flash was unsuccessful, then we paid $4000 to change the torque converter. The Tech stated that this was the GM suggested fix, but noted that we are changing the fluid also which could mask the issue if it is the valve body causing an issue. The replacement torque converter and fluid did somewhat reduce the issue for a short period of about 2 months before it has returned as it did before. The next option from the dealership is in excess of $8,000 for a remanufactured transmission which is outside our reasonable spend, when we dont expect the remanufactured transmission will have any better valve body components. The recent recall did not cover my gas 6.2L sierra 1500, although it clearly is insufficient stating that it just a warning that there is a safety risk present. The valve body of the transmission appears to be an issue across all models and the recall addresses that it is present. We continue to drive this as the primary family vehicle with the hesitation and jerking present as GM dealer offered no support other than $8,000 remanufactured transmission on top of the $4000 we already spent. I believe the recall was insufficent in covering the Gas models with the exact same transmission and known issue. I also believe the offered solution continues to put those driving at risk.

Filed Jan 3, 2026 · Engine, Transmission · NC

I own a 2021 GMC Sierra 1500 equipped with the 6.2L L87 V8 engine and 10-speed transmission. The vehicle exhibits the following issues: Persistent lifter ticking noise audible from the driver-side wheel well, even when the engine is warm. Rough idle that is noticeable at stops and low-speed conditions. Transmission shifting problems, specifically harsh or delayed shifts when downshifting from 3rd to 2nd gear during deceleration. These symptoms raise concerns about potential lifter failure and transmission defects. I am aware of GM’s recall (25V‑274) and the federal safety agency Engineering Analysis EA25007, but my vehicle’s build date (January 2021) currently falls outside the official recall window. Given the similarity of symptoms to those under investigation, I believe my vehicle may be affected by the same defect. Safety Concern: The rough idle and shifting hesitation could lead to unexpected loss of power or unsafe driving conditions, especially during deceleration or merging. Request: Please include this complaint in EA25007 and consider expanding the recall to cover earlier builds. I am willing to provide service records, videos, and additional documentation upon request.

Filed Nov 13, 2025 · Electrical, Engine · FL

I am an active U.S. Air Force member. My 2021 GMC Sierra 1500 failed GM Recall N252494003 on Sept 29, 2025 (L87 engine loss of propulsion). GM states this defect can cause sudden engine failure and loss of propulsion, increasing crash risk. Despite the confirmed failure, Ocean Cadillac (Miami, FL) told me to keep driving the unsafe vehicle and refused all Courtesy Transportation. The Service Manager admitted in writing that the engine failed, the defect can cause loss of propulsion, and the replacement engine is delayed under GM National Control for up to 3 months — yet they still denied me a loaner or rental. His statements contradict the GM documents he attached: • GM Bulletin DCS7222 says Courtesy Transportation CAN be provided during L87 recall downtime and dealers MUST consider loaners/rentals. • GM FAQ N252494002 says Courtesy Transportation IS available for this recall. • GM FAQ lists recall symptoms (check engine light, hesitation, high RPM, reduced power) — NOT battery drain. • GM states: “If the engine fails, the vehicle WILL lose propulsion.” Ocean Cadillac ignored these rules and put me back on the road in a known unsafe vehicle. As an American manufacturer, GM has a responsibility to protect American drivers. Their failure to follow recall procedures placed me, my family, and other motorists at risk. I request the federal safety agency investigate whether GM/Ocean Cadillac are complying with recall safety requirements and whether customers are being told to drive unsafe vehicles after confirmed failures.

Filed Jul 8, 2025 · Transmission · 119,000 miles · AZ

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 75 MPH, the vehicle jerked and downshifted to overdrive. The message "Engine Power Reduced" was displayed on the instrument panel. The driver depressed the accelerator pedal, but the vehicle failed to exceed 4 MPH. The vehicle was taken to the dealer, where it was diagnosed that the valve body failed, which caused the transmission to fail. The vehicle was repaired. While the contact was driving home after the vehicle was picked up, the vehicle jerked and hesitated. The dealer was contacted and informed the contact that if the check engine warning light becomes illuminated the vehicle could be diagnosed. After several days, the check engine warning light illuminated, and the vehicle was taken to the dealer where it was diagnosed that the shutter valve had failed and needed to be replaced. The vehicle was repaired. The contact stated that the failure persisted. The contact received the federal safety agency Campaign Number: 24V797000 (POWER TRAIN). The vehicle was repaired; however, the failure persisted. The manufacturer was made aware of the failure and offered the contact assistance with the transmission repair. The failure mileage was approximately 119,000.

Filed Jun 26, 2025 · Engine · 83,000 miles · NM

The contact owns a 2021 GMC Sierra 1500. The contact stated that occasionally while attempting to start the vehicle, the engine hesitated to turn over. The contact stated that the failure progressed, and the vehicle no longer started as needed. The check engine warning light was illuminated. The contact stated that two local dealers were contacted; however, the contact was advised that to diagnose or repair the vehicle, might take several months. The vehicle was towed to a local independent mechanic, where it was diagnosed with camshaft sensor failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 83,000.

Filed Jun 17, 2025 · Transmission · PA

The contact owns a 2021 GMC Sierra 1500. The contact stated upon starting the vehicle and shifting to drive(D) in the morning, the transmission hesitated to shift to second gear and then shifted harshly. There was no warning light illuminated. The vehicle was taken to the dealer, where it was test-driven, but the failure could not be duplicated. The contact stated that the failure occurred once a day on first start-up of the vehicle and upon shifting to drive(D). The vehicle was taken back to the dealer over the weekend, and the dealer was able to duplicate the failure on first start-up of the vehicle and upon shift to drive(D). The dealer related the failure to TSB Number: 16-NA-361; and informed the contact the manufacturer had not made a repair available. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the federal safety agency Hotline to file a complaint. The failure mileage was unknown.

Filed Apr 9, 2025 · Electrical · IN

This truck, along with many others, has had wiring harness issues. My truck has fought this issue within the first six months of owning the truck. Since Jan 2025 it has left me stranded 3 times to be towed, and in the shop a total of 6 times for wiring harness issues. Rubbing that GM is 100% aware of how its designed. This has caused the truck to hesitate, shake, lunge, go in and out of gear severely hard then shut off while driving. All three time this happened to me recently i was on the interstate. GM has work orders out with all the codes and symptoms but wont do anything about it. Yes, i am out of warranty, but i am now paying over $5,000 for a new harness to be installed by a different dealer. The dealer that had always worked on this truck requested $8,100 so i called a new GM shop. This is a large issue and they keep turning their back and not addressing the issue and putting drivers at risk! Can provide last diagnostics and can request all notes from Stoops Buick GMC in Muncie Indiana, i have a rather large file there on this truck.

Filed Feb 11, 2025 · Transmission · 8,000 miles · TN

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at various speeds and depressing the accelerator pedal, the vehicle hesitated to respond and shuddered. The vehicle was taken to the dealer, where the fuel tank was cleaned, and the contact added fuel treatment to the fuel, as recommended by the dealer; however, the failure recurred. The contact stated that while driving from a complete stop, uphill, and while driving 50 MPH, the vehicle shuddered and experienced erratic transmission shifting. The check engine warning light was illuminated. The vehicle was taken to Dixie Buick GMC (14565 S Tamiami Trl, Fort Myers, FL 33912); where it was determined that the vehicle was experiencing a abnormal shudder. The dealer replaced the transmission fluid; however, the failure persisted. The contact stated that the failure had become progressively worse and mostly occurred at 1,200 RPM. The dealer was contacted, and an appointment was scheduled for diagnostic testing. The vehicle was not diagnosed or repaired. The contact related the failure to the federal safety agency Campaign Number: 24V797000 (Power Train); however, the VIN was not included. The manufacturer was notified of the failure. The failure mileage was approximately 8,000.

Filed Jun 26, 2024 · MS

The transmission/torque converter is causing (bucking, kicking, jerking, slipping, difficulty when taking off, shuddering during driving, fishbite, and chuggle). Its becoming a safety hazard now because its putting me and others at risk for an accident. The vehicle will hesitate to go in which if traffic may be rear ended by another vehicle. During weather/rain the vehicle will lose traction and the rear wheels will spin causing an accident. Problem has been reported to dealership multiple times and the only solution they can provide is keep driving the vehicle. Vehicle has no warning lights at all or any other symptoms of problems prior to when the components started to fail. The issue first happened around February 2024 and remains to be an issue to this present day. I've been the dealership more than 6 times with no solution/fix. I'm concerned for my safety now and need this issue addressed ASAP.