2021 GMC Sierra 1500 Problems

What owners report

Owners of this model year most often report engine-related problems: lifter and camshaft failures, excessive oil consumption, engine noise and, in some cases, engine replacement. Transmission complaints are the next most common, typically describing harsh or delayed shifting, shuddering, and loss of motive power around 60,000-70,000 miles. A separate cluster of complaints covers the power tailgate opening on its own.

1. 1
   Engine

   Engine lifter/camshaft failure and internal engine damage

   • 210 complaints (35%)
   • median 66,456 mi at 4.5 yrs old (47 state mileage)
   • 2 mention a crash, fire or injury
   • owner-quoted repair $6,800 (median of 11 quotes)
   • filed 2021–2026

   Complaints describe knocking, ticking or popping noises from the engine, rough idling, misfires and a check engine light, sometimes followed by loss of power or a stall. Several owners report the dealer diagnosing collapsed or failed lifters and camshaft wear, with repairs ranging from lifter replacement to cylinder head or full engine replacement. A number of owners tie their experience to the 6.2L V8 connecting rod/crankshaft recall and report that parts were not yet available or that their vehicle was not covered. Spread across the range, from under 20,000 miles to well past 100,000, with many reports between roughly 40,000 and 90,000 miles.

   Recall 25V2740001 related service bulletin

   What to check: Ask whether the vehicle's VIN is included in recall 25V274000 and whether any inspection or repair was completed. Listen for ticking or knocking at idle and cold start, and check oil level and service records for consumption complaints.

   2 excerpts from owner complaints in NHTSA records

   “The contact owns a 2021 GMC Sierra 1500. The contact stated that the engine was previously replaced under warranty. The contact stated that the vehicle had been experiencing excessive oil consumption and required three quarts of oil every 30 days. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the part to do the recall repair was not yet available. …”

   NHTSA complaint #11681250, filed 2025-08, 129,000 miles

   “The contact owns a 2021 GMC Sierra 1500. While the contact's husband was driving at an undisclosed speed, the contact noticed an abnormally bumpy ride. The contact felt as if the vehicle was driving over rocks. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. …”

   NHTSA complaint #11691802, filed 2025-10, 80,000 miles
2. 2
   Transmission and drivetrain

   Transmission shudder, hard shifting and sudden loss of power

   • 92 complaints (15%)
   • median 65,657 mi at 4.4 yrs old (20 state mileage)
   • owner-quoted repair $1,500 (median of 5 quotes)
   • filed 2021–2026

   Owners describe jerking, hard or erratic shifting, shuddering and shaking, and occasional failure to accelerate, sometimes with a reduced-power message. Complaints mention valve body failure, torque converter and output shaft speed sensor diagnoses, and in some cases transmission replacement. Several owners say problems continued after a recall software update was performed. Mostly reported between about 40,000 and 120,000 miles, often while driving at highway speeds.

   Recall 24V797000Recall 26V0830003 related service bulletins

   What to check: Ask whether recall 24V797 (and any follow-up) was completed and keep the paperwork. During a test drive, note any shudder, delay or harshness on light and moderate acceleration, and check for stored transmission codes.

   2 excerpts from owner complaints in NHTSA records

   “The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at 55 MPH, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The contact became aware of an abnormal sound, and the check engine warning light was illuminated. The vehicle was driven to the shoulder of the road. The contact inspected the vehicle and connected a portable diagnostic tester to the vehicle. The contact retrieved a pressure fault code. …”

   NHTSA complaint #11772486, filed 2026-10, 106,554 miles

   “The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 24V797000 (Power Train); however, the dealer was unable to complete the recall and returned the vehicle to the contact in a worse condition than when the contact had dropped the vehicle off at the dealer. The contact stated that while attempting to drive the vehicle off the dealer parking lot, the check engine and reduced power warning lights flashed on the instrument cluster. …”

   NHTSA complaint #11650551, filed 2025-03, 114,000 miles
3. 3
   Other or unknown

   Power tailgate opening on its own

   Mentioned in 10 of 60 sampled complaints

   Complaints describe the electronic tailgate unlatching and opening while the vehicle is parked, and in some instances while driving, with a tailgate-open message appearing. Some owners report water intrusion damaging the tailgate panel buttons so the gate will not open, and others report the inner gate or release button behaving incorrectly. Dealers in some cases could not determine a cause; some owners were told their VIN was not covered by a related campaign. Typically reported between roughly 20,000 and 90,000 miles, on both parked and moving vehicles.

   1 related service bulletin

   What to check: Test the tailgate release buttons, the key fob and the inner gate several times, and check whether the buttons feel loose or show water damage. Ask whether any tailgate-related campaign applies to the VIN.

   2 excerpts from owner complaints in NHTSA records

   “The contact owns a 2021 GMC Sierra 1500. The contact stated while the vehicle was parked and turned off, the electronic rear tailgate door erroneously unlatched and opened. The contact stated that the failure had occurred on several occasions. The cause of the failure was not yet determined. The local dealer and manufacturer were notified of the failure. The failure mileage was 58,000.”

   NHTSA complaint #11602610, filed 2024-07, 58,000 miles

   “The contact owns a 2021 GMC Sierra 1500. The contact stated that the inner tailgate door failed to open while pressing the release button. On several occasions while pressing the release button, the inner door would lower down. The cause of the failure was not yet determined. The manufacturer and local dealer were notified of the failure, but no assistance was provided. The failure mileage was 45,000.”

   NHTSA complaint #11595515, filed 2024-06, 45,000 miles
4. 4
   Engine

   Excessive oil consumption and low oil warnings

   • 69 complaints (12%)
   • median 56,802 mi at 4.8 yrs old (13 state mileage)
   • owner-quoted repair $8,050 (median of 6 quotes)
   • filed 2021–2026

   Owners report needing to add oil frequently, low oil pressure or low oil level warnings, and an oil smell while driving. Complaints describe repeated dealer visits and oil consumption tests that were not completed or could not duplicate the condition. Reported from about 30,000 to 130,000 miles; one owner described adding several quarts within a month.

   Recall 25V274000

   What to check: Check the dipstick level and look for oil residue or smell around the engine bay. Ask whether an oil consumption test was ever performed and whether oil changes used the viscosity specified in any updated owner information.

   2 excerpts from owner complaints in NHTSA records

   “The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the low oil warning light illuminated. The vehicle was taken to the dealer but was not diagnosed or repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 67,600.”

   NHTSA complaint #11662133, filed 2025-05, 67,600 miles

   “The contact owns a 2021 GMC Sierra 1500. The contact stated that the vehicle was experiencing excessive oil consumption. The low oil pressure warning light was illuminated. The vehicle was taken to the dealer, but the failure could not be duplicated. The vehicle was taken to the dealer several times, where an oil consumption test was performed. The contact stated that the oil consumption test was not completed. …”

   NHTSA complaint #11659055, filed 2025-05, 44,000 miles
5. 5
   Engine cooling

   Engine stalls or loses power, sometimes tied to cooling

   Mentioned in 4 of 60 sampled complaints

   Complaints describe the engine stalling or dropping into reduced power, with a 'shift to neutral and restart' message, and in some cases overheating. Dealers diagnosed coolant control valve failure in several reports, and some owners say parts were on backorder or that the repair was not covered by a special coverage program because their VIN was excluded. Mostly reported between roughly 40,000 and 95,000 miles.

   1 related service bulletin

   What to check: Ask whether the coolant control valve has been replaced and whether any special coverage applies to the VIN. Check for coolant residue, and watch the temperature gauge during a longer test drive.

   2 excerpts from owner complaints in NHTSA records

   “The contact owns a 2021 GMC Sierra 1500. The contact stated that there was an abnormal change with the RPM. There were no warning lights illuminated. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the part to do the recall repair was not yet available. The local dealer was contacted. The dealer received an email from the manufacturer, but the verbiage was incorrect to move forward with the repair. …”

   NHTSA complaint #11676253, filed 2025-07, 39,000 miles

   “The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at various speeds, the check engine warning light illuminated, and the engine fan activated and operated at a very high velocity. Additionally, the message Engine Power Failure message was displayed, and the vehicle stalled. The vehicle was taken to the local dealer who diagnosed that the engine coolant control valve was faulty and needed to be replaced. The contact was informed that the parts were on backorder and no repairs were performed. …”

   NHTSA complaint #11667437, filed 2025-06, 45,000 miles

Buying note. These trucks are commonly reported for engine and transmission work at moderate mileage, so service records and recall completion matter more than cosmetics. Verifying recall status by VIN and having a pre-purchase inspection that includes a scan for stored codes is a reasonable step before buying.

Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.