2021 Chevrolet Silverado 2500 Problems

What owners report

Owners of the 2021 Silverado 2500 most often describe transmission and driveline problems, especially with the 10-speed automatic in diesel trucks: hard or delayed shifts, the dash showing "Shift to Park" when the truck is already in park, and in some cases momentary rear-wheel lockup. A second, very common theme is the power tailgate opening or cycling on its own, which several owners link to a published recall. Complaints also cover brake squeal, diesel emissions and DEF heater faults, and occasional no-start or engine failure reports at higher mileage.

1. 1
   Transmission and drivetrain

   Transmission harsh shifting, gear loss and rear wheel lockup

   • 24 complaints (27%)
   • median 100,000 mi at 4.0 yrs old (5 state mileage, few)
   • filed 2023–2026

   Owners describe rough or delayed shifts, sudden downshifts, high rpm before a shift, and intermittent loss of drive or a momentary rear-wheel lockup at highway speed. Several say the truck dropped into a fail-safe or limited gear, or was towed to the dealer. Some complainants report that a software update performed under a recall did not resolve the symptom, and that dealers described similar behavior on other trucks as a known condition. Reported from about 25,000 miles up into the 110,000-122,000 mile range, mostly on diesel trucks, often appearing without warning.

   Recall 24V7970004 related service bulletins

   What to check: Ask whether the transmission control module software campaign associated with 24V797000 was completed, and have a scan tool check for stored transmission codes. Test drive at highway speed and note any harsh or delayed shifts.

   2 excerpts from owner complaints in NHTSA records

   “My 10L1000 transmission had a catastrophic failure internally which caused it to rough shift, sudden down shifting, not want to shift into gear at all, and high engine rpm prior to roughly shifting. I took it to the Chevy dealers mechanic the very next business day, only to find out that from the mechanic that this is a common occurrence with Chevy transmissions in my truck and google also verified this to be a common problem. The mechanic from the Chevy dealership also stated that there was larger metal chunks than normal. …”

   NHTSA complaint #11752243, filed 2026-07

   “While traveling at highway speed on the interstate in my 2021 Chevrolet Silverado 2500 HD (approx. 120,000 miles), the vehicle experienced a sudden hard jolt followed by a momentary rear wheel lockup. This occurred without warning. Immediately after, the transmission defaulted into a fail-safe condition and became locked in 4th gear. The vehicle would move but could not shift properly, resulting in abnormally high RPM and engine load at highway speeds. I was forced to continue driving several miles in this condition to reach a safe exit. …”

   NHTSA complaint #11720857, filed 2026-02
2. 2
   Latches, locks and linkages

   Power tailgate opens or cycles on its own

   • 15 complaints (17%)
   • median 39,500 mi at 4.1 yrs old (4 state mileage, few)
   • filed 2023–2026

   Owners describe the power tailgate unlatching or opening and closing repeatedly by itself, parked or moving, sometimes several times in a row and occasionally slamming down. Some removed the tailgate fuse or strap to stop it. Several complainants cite recall 24V060000 and say their VIN was not covered; others report the dealer declined to repair it. Reported anywhere from around 10 mph or parked situations up to about 74,000 miles, and frequently described as intermittent.

   Recall 24V060000

   What to check: Check whether the tailgate recall 24V060000 applies to the VIN, and watch the gate through a lock/unlock and door-open cycle to see whether it moves on its own.

   2 excerpts from owner complaints in NHTSA records

   “I opened my passenger front door to load and the tailgate opens and closes by itself but doesn’t and remains open. I physically shut the tailgate and it opened again by itself. I started my truck to see if it would stop. It didn’t stop until I put my truck in reverse to back out of the garage. After I backed out and the tailgate stopped open. I closed it and the tailgate will not open by pressing the button on the tailgate. It will open if I use my key fob.”

   NHTSA complaint #11767859, filed 2026-09

   “Tailgate. Yes it can be inspected. It opens and closes randomly , I was going on to the freeway for work when I suddenly received a notice that the tailgate was opening. when I pulled over the gate was open and all the contents were at the end of the truck bed, power saws and equipment almost flew out into traffic! I then called the dealer who told me there was a recall and to bring it in, so I did and when I pulled in the service department the tailgate opened upon entering service area. …”

   NHTSA complaint #11581794, filed 2024-04
3. 3
   Brakes

   Brake noise and intermittent loss of pedal

   • 12 complaints (14%)
   • median 15,000 mi at 1.5 yrs old (1 states mileage, few)
   • 1 mention a crash, fire or injury
   • filed 2021–2026

   Many owners describe loud, persistent rear brake squeal at low speed that dealers said could not be addressed, or attributed to normal brake wear. A smaller group describes the pedal going to the floor or needing excessive pressure, with braking returning after a restart or a tow to the dealer; one mentions the parking brake failing to release. Squeal reported from as low as about 5,500 miles and around 15,000 miles; pedal complaints appear at varied mileage including low odometer readings.

   Recall 21V758000

   What to check: Ask about brake work history on the rear brakes, and confirm whether the brake pressure modulator valve recall 21V758000 was performed. Test the pedal feel on a long, firm stop.

   2 excerpts from owner complaints in NHTSA records

   “My fiance started the truck. Drove about 2 miles from my mothers house, the check engine light came on. The traction control light came on and then she informed me that it felt like all braking power was lost. Truck is being towed to dealership. Could have killed or badly injured someone.”

   NHTSA complaint #11436857, filed 2021-10

   “Brakes: the brakes do not stop the vehicle without excessive pressure to the pedal. Especially carrying a trailer with the exhaust brake & trailer brakes in effect. Takes excessive distance for vehicle to stop. Pedal must be pressed 3/4 to the floor for it to start to apply brakes. It is extremely difficult to stop this vehicle at any speed over 45mph. Have not taken to dealer, was expecting a recall but none until now. …”

   NHTSA complaint #11428269, filed 2021-08
4. 4
   Electrical system

   Diesel emissions and DEF heater faults with speed limiting

   • 15 complaints (17%)
   • median 47,500 mi at 4.6 yrs old (2 state mileage, few)
   • 1 mention a crash, fire or injury
   • filed 2021–2026

   Diesel owners describe a "Service Emissions System" message with a countdown to reduced speed, loss of power on the highway, and codes traced to the reductant (DEF) heater or a melted harness connector at the tank. Complaints note parts on backorder and long waits, and some say the repair was not covered under warranty. Mostly reported between about 68,000 and 100,000 miles on diesel trucks, often during highway driving.

   2 related service bulletins

   What to check: Ask for any emissions-related repair history and check whether the DEF tank heater and its wiring connector have been replaced. Have any stored emissions codes read before purchase.

   2 excerpts from owner complaints in NHTSA records

   “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). …”

   NHTSA complaint #11700011, filed 2025-11

   “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. …”

   NHTSA complaint #11504538, filed 2023-01
5. 5
   Transmission and drivetrain

   "Shift to Park" message when already in park

   • 12 complaints (14%)
   • median 62,500 mi at 4.8 yrs old (2 state mileage, few)
   • 1 mention a crash, fire or injury
   • filed 2021–2026

   Owners report the truck displaying a "Shift to Park" or "Service steering column lock" message after the lever is already in park, which can prevent the vehicle from fully shutting off or the doors from locking. Some describe leaving the truck unlocked so they can get back in later. A few mention that repeated shifting between park and drive does not clear it. Reported from roughly 25,000 to 72,000 miles, becoming constant over time rather than occasional.

   What to check: With the truck running, shift into park and confirm the dash clears without a "Shift to Park" prompt and that the truck powers off fully. Repeat a few times.

   2 excerpts from owner complaints in NHTSA records

   “My truck has been having the Shift To Park warning for quite a while now. Truck has roughly 72000 miles. Before it would happen intermediately, now it happens all the time. Often I have to leave my truck unlocked for long periods of time due to this malfunction. Hoping my battery will still have power to restart the next time. Reading and researching this issue online, it is a known fact that this is a widespread problem and GM needs to step up and issue a recall.”

   NHTSA complaint #11658868, filed 2025-05

   “The contact owns a 2021 Chevrolet Silverado 2500. The contact stated that upon reaching his destination and shifting the vehicle into park, the vehicle failed to recognize that the gear shift lever had been moved to park (P). The contact stated that the Please Shift to Park message was displayed and the doors were unable to be locked. The vehicle returned to normal functionality, but the failure became a regular occurrence. No warning lights were illuminated. The vehicle was not taken to the dealer or an independent mechanic. …”

   NHTSA complaint #11653956, filed 2025-04, 25,000 miles

Buying note. Used 2021 Silverado 2500 shoppers should verify which of the open recalls for this model year were actually completed, and drive the truck at highway speed long enough to judge transmission behavior. On diesel models, confirm the emissions and DEF heater history 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.