2021 Chevrolet Silverado 1500 Powertrain (other) Problems

On August 22, 2025 the malfunction indicator lamp (code: P146B Evap. purge pump) illuminated with no noticeable change. Ran codes at auto zone which stated engine failed and emissions not ready. August 25, 2025 drove to certified Chevy dealer dropped off vehicle and showed the service advisor the fix finder test results from auto zone as well as the illuminated indicator lamp (check engine light). August 26, 2025 picked up my vehicle with receipt stating "found dtc's P146b and P1467 stored in ECM (engine control module) for evap purge pump fault. inspected evap canister for any signs of fuel and none were found. replaced evap purge pump per special policy #N232395310. Cleared dtc and road tested vehicle to verify repair". September 9, 2025 my engine indicator light illuminated and my engine entered limp mode, a safety feature which reduces cylinder output/capacity. September 12, 2025 while in limp mode, I returned to the service dealer and informed them of the reduced power (limp mode) and my confusion as the second engine symbol that has been illuminated is in a different area than the first and my truck has ONE engine. (editor note: malfunction indicator lamp is for the emissions). My original transmission (8L90) was replace, because my vehicle was under power train warranty and the service advisor took it upon himself to approve the disassembly of my running, in good condition 8L90 transmission without consulting me or my approval. the 8L90 was "discontinued" for the 2020-2022 years without recall come to find out (sarcasm). I now have a new transmission (8L86-85) with the "special coverage" part (#N232395310) still connected, only now I have NO additional powertrain coverage for a new transmission, but the "special coverage" originally issued in 2023, BY MAIL, for 15 yr/150,000miles has extended two years plus mileage. (15 yr / 152,955) .The "special coverage" part should NOT affect the engine! Engines produce power/HEAT not CO2 . Sarbane - Oxley Act.

NHTSA ID

11755329

Incident

Aug 25, 2025

The contact owns a 2021 Chevrolet Silverado 1500. The contact stated that while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The contact stated that there was an abnormal sound coming from the vehicle and the vehicle was jerking erratically. The contact stated that the transmission was shifting hard, and the vehicle drove abnormally rough. No warning lights were illuminated. The vehicle was taken to the dealer; however, the failure was not duplicated. The failure was persistent. The manufacturer was not made aware of the failure. The failure mileage was approximately 49,000.

NHTSA ID

11754700

Incident

Aug 13, 2024

Mileage

49,000 mi

2021 Chevy Silverado 5.3 trail boss lifters has failed on this driver two times while driving on highway engine lost power with my family in the vehicle. Dealer warranty fixed lifter the first time lifter went out at 1100 miles. The vehicle has failed again with multiple lifters going out and camshaft needing being replaced also on my extended warranty at 73000 miles. I do not want to take this vehicle back in my possession as it has put me and my family at risk twice being stuck on highway with no power.

NHTSA ID

11754540

Incident

Jul 17, 2026

On or around XXX a my 2021 Silverado started making a rattling sound from the engine. The truck began to stall and the engine shut off three times while driving. I attached scanner the next day and the track showed P00011 and P00016 codes. Those codes are for the Camshaft Sensor and the Crankshaft Sensor. I went online and did research about the two codes and discovered there had been a couple recalls for these codes concerning my year model truck: (Recall Number 25V-274; GM: Campain N252494000). NHTSA Engineering Analysis EA25007 or RQ26001 I spoke with the Dealer I purchased vehicle from (Lynn Layton Chevrolet - Decatur, Al)and they said they will not begin repairs until they receive payment from GM or myself. I then spoke with Tyler at GM Corporate Customer Service. He said my VIN was not included in the GM Campaign|Recall. I asked why not because it is a 2021 Silverado and I’m having the exact same problems as vehicles included in the recall. He said because they checked their system and the parts used on my truck were from a different manufacturer than those included on the recall. I said that shouldn’t matter because my truck is having the same exact problems. I asked him to check and see if GM would be able to provide financial assistance to have motor repaired or replaced. Tyler told me that GM will not do repairs - they will only replace the engine. He said GM would not provide any financial assistance because my truck has 170k plus miles on it. I informed Him that I had previously taken my truck to Lynn Layton Chevrolet about these symptoms and it was diagnosed as transmission/torque converter problem. They changed transmission fluid and charged me ~$700. I then asked if GM would authorize a “Goodwill Replacement”. He said they would not. I called Lynn Layton Decatur back and asked how much would engine and reps if I have to pay for it. They said 10k -12k A local mechanic said he will fix for $6,000. Please help me get this resolved. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION

NHTSA ID

11753677

Incident

Jun 10, 2026

The contact owns a 2021 Chevrolet Silverado 1500. The contact stated that while driving approximately 30 - 60 MPH, the transmission failed to shift properly, and the vehicle hesitated while depressing the accelerator pedal. A dealer was contacted. The vehicle was taken to the dealer to be diagnosed, and the contact was informed that the valve body needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to report the failure. The approximate failure mileage was 105,000.

NHTSA ID

11753288

Incident

Jul 17, 2026

Mileage

105,000 mi

Transmission needs to be replaced at 77000 miles!! A KNOWN problem with this make/model/year and NOTHING is being done!!!!!!!!!!!!!!!!

NHTSA ID

11750803

Incident

Jul 16, 2026

I have a 2021 Chevrolet Silverado 1500 with a 3.0 Duramax diesel engine, Have had a check engine light intermittent a couple times. Vehicle went into limp mode. Had the diagnostic code read; P1010. Code P1010 shows an engine coolant flow control valve position sensor exceeded minimum learning limit. General Motors has issued a special warranty N252508341covering 2021-2023 Silverado 1500 for this part ( LM2 coolant control valve replacement ) with a 15 year and 150,000 mile limit. I took my vehicle to the Chevrolet dealer and they said my VIN number was not covered. It would be a $1900 repair. I have read of numerous other of same vehicles listed under the special warranty, yet GM has excluded these VIN numbers as well. This is a known defect, GM has covered some but not all. Yet many are NOT covered yet having the same problem. I am not able to reach anyone at GM to talk about this issue. It needs to be addressed.

NHTSA ID

11748870

Incident

Jul 6, 2026

Transmission shutter at low speed acceleration

NHTSA ID

11747289

Incident

Jun 1, 2026

My 2021 Chevrolet Silverado RST 4x4 5.3L V8 was a Certified Pre-Owned vehicle purchased through a GMC dealership, strictly maintained by certified GMC service departments, and had its torque converter replaced one year prior in accordance with a manufacturer Technical Service Bulletin (TSB). One week before a scheduled round-trip journey from Alabama to North Carolina, the truck underwent a comprehensive multi-point inspection, oil change, and tire rotation at an authorized Chevrolet dealership. While driving on the highway, I came to a complete stop due to an accident ahead, but when traffic resumed a forward-moving pace, the drivetrain completely lost the ability to propel the vehicle without any prior warning signs or symptoms of mechanical failure. While immobilized and contacting 911 and towing services, I attempted to cycle through all drive modes—including Auto, 4-High, 4-Low, and 2WD—but none succeeded in transferring power to the wheels; though the engine would still rev, no power reached the tires. No dashboard warning lights illuminated prior to the drivetrain failure, though a check engine light did appear after the vehicle became immobile when I was switching through drive modes. Because there was no available highway shoulder or exit to seek safety, and due to the sudden nature of the mechanical failure, emergency vehicles and tow trucks could not safely divert traffic or move the vehicle in time, resulting in a severe rear-end collision that caused a total loss. The vehicle has not yet undergone a mechanical inspection, but it is currently under a 60-day hold for examination by insurance adjusters and legal counsel, and it remains available for a formal teardown upon request.

NHTSA ID

11745764

Incident

May 17, 2026

10 speed transmission failed at 70K miles. Metal found in the torque converter. Manufacturer recommended routine maintenance was performed on transmission. There needs to be a recall on 2020 to 2021 vehicles with the 10 speed transmission due to the reporting of safety issues of the vehicles locking up while driving. I was lucky to feel the issue happening and getting off the road before it was able to lock up on me causing serious injuries. This needs to be addressed and taken seriously before someone loses their life. Best regards, [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11744565

Incident

Jun 8, 2026

The truck started backfiring and shuddering. Took it to the mechanic and with only 112000 miles I am being told it needs a new engine. It is the 6.2l motor.

NHTSA ID

11743395

Incident

Jun 6, 2026

Loud ticking noise and power loss. Transmission shift slips from 2nd to 3rd . Called factory and dealership for check up. Said no problem… Told to Change oil. Did this, NO CHANGE.

NHTSA ID

11743104

Incident

May 2, 2026

When i first purchased the vehicle off the lot a few years back (its a 21, so probably in 22?) Brand new off the lot minimal miles. Within the first few months we started having issues with the power wanting to shift down. We took it in, the dealership found nothing wrong with it and cleared the codes. This happened a few more times. The last 2 times I took it in. They mentioned that there were recalls on it and could possibly be causing the issue. Took care of that (last august- have docs. to prove it as along with what they did and what we stated). Fast forward now 2 months ago (April of 25) and it starts acting up again and wants to downshift, shifting hard, stuttering and not wanting to drive, the same things we have been complaining about since beginning with lights on etc. However, this time we tried to shut it off and give some down time to get back home. After about 10 mins, we went to start the truck to get it home, and it would not start. We had it towed to the dealership. Once they got it, after 2 weeks of waiting we were finally presented with, the starter went out and the wiring box needed to be replaced (this has to be done before they can look into the original problem again) (because without those 2 things fixed, they wont be able to do) it is now June. I took the vehicle home, due to not having funds to fix right away. After doing some research and some digging, it would appear that the issues that we are having with the truck are issues that are already being recalled on this specific truck and model. However, for mine it is not, because I have the 2.7 l turbo and not the 6.8. THere have been numerous complaints about the known issue.(which i found out is the other wiring by the engine that is being chafed which is causing the wires to break and causing the other box and alternator to go and be replaced). If you replace it fries all again. Why is the 2.6 engine problem thats reported not recalled but rest is and it is known. I also see this online

NHTSA ID

11742660

Incident

Aug 8, 2025

Loud ticking noise and power loss. Transmission shift slips from 2ed to 3rd .Recall to factory for check up. Said no problem? Changed oil. They say it was good. It is not.

NHTSA ID

11742567

Incident

Oct 1, 2025

My 2021 Chevrolet Silverado 1500 with the 3.0 diesel is experiencing constant high running engine fan, engine power reduced notification on the dash, fluctuating temperature and is showing a P1098 code indicating the coolant control valve needs replaced. GM has issued a special coverage on this part, which my truck is well withing the parameters for. However, GM tells me the VIN isn't associated with the special coverage. I have spoken with other owners who have the same year / engine vehicle as I do, and GM replaced their part for free under the special coverage. I have not been giving any explanation as to why my vehicle isn't covered even though the bulletin N25250834 clearly states my vehicle and year. I escalated to the GM executive level and have failed to get my coolant control valve replaced. The vehicle reducing engine power is a major safety concern in traffic as well as the obvious over heating issue. GM is blatantly mishandling the situation.

NHTSA ID

11738805

Incident

Apr 1, 2026

The contact owns a 2021 Chevrolet Silverado LD Crew. The contact stated that while reversing the vehicle, the rear end locked up. Also, when accelerated, the vehicle jerked forward and stalled. When the vehicle is shutdown and restarted the vehicle. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The approximate failure mileage. 64,900.

NHTSA ID

11738796

Incident

May 18, 2026

Mileage

64,900 mi

47,000 miles and the transmission coolant lines are weeping and need to be replaced.

NHTSA ID

11738346

Incident

Apr 24, 2026

I am submitting a formal safety complaint regarding an electrical system failure on my 2021 Chevrolet Silverado with approximately 61,000 miles. I brought the vehicle to Taylor Grubaugh Chevrolet of Waynesville after the check engine light illuminated. The dealership diagnosed a premature wiring harness failure caused by chafing. They also stated that this issue is known to affect multiple GM vehicles and is documented in Technical Service Bulletin 21 NA 149. Wiring harness failure presents a significant safety concern. A compromised harness can lead to erratic electrical behavior, reduced engine performance, stalling, or sudden loss of power while driving. With that the concern a possible vehicle malfunction or losing power in traffic came to light. The dealerships service department confirmed the problem, verified the wiring harness failure, & referenced the applicable GM technical bulletin. The vehicle was inspected by the authorized Chevrolet dealership. GM declined to cover the repair. No police, insurance, or other third party inspections have been conducted. Despite acknowledging that this is a documented & recurring issue across GM models, the GM informed me that the repair would not be covered under warranty or recall. At only 61,000 miles, a wiring harness failure due to chafing is not consistent with normal wear & tear & instead suggests a premature defect. Given that this is a known and documented defect, I believe it should be recalled. After further research, I discovered that this issue is far from isolated. There are more than 1,500 complaints filed with the Better Business Bureau and approximately 800 complaints submitted to NHTSA reporting the same or similar wiring harness failures across GM vehicles. The volume of complaints strongly suggests a widespread defect that may pose ongoing safety risks to consumers.

NHTSA ID

11737889

Incident

Mar 31, 2026

LIFTER FAILURE AT 50,100 MILES- JUST OUT OF POWERTRAIN WARRANT BY 136 DAYS. FAILURE OCCURED ON FREEWAY. AFTER HEARING METALLIC SOUND SERVICE BRAKE SYSTEM LIGHT, TRACTION CONTROL AND SERVICE ENGINE LIGHT CAME ON. THIS OCCURED 5/3/26.

NHTSA ID

11735778

Incident

May 2, 2026

Vehicle: 2021 Chevrolet Silverado VIN: [XXX] Mileage at time of incident: Approximately 68,000 miles Date of incident: April 24, 2026 Approximate speed: 75 mph Weather/road conditions: Clear, sunny day Was the vehicle towed? No Did the engine restart? Yes My 2021 Chevrolet Silverado experienced a sudden loss of power and stalled while I was driving on the highway at approximately 75 mph. The weather was clear and sunny, and road conditions were normal. This created a serious safety concern because the vehicle lost power while traveling at highway speed in traffic and could have caused a crash. The vehicle did restart after the incident and was not towed, but it had to be taken in for service after the power loss/stalling event. The dealership later advised that the oil was low on the dipstick and stated they would change the oil and complete a recall/service update. However, I have maintained the vehicle with regular oil changes, and at the time of the incident, the vehicle’s oil life monitor still showed approximately 50% oil life remaining. I do not believe this should be dismissed as a simple lack-of-maintenance issue. I am concerned that the sudden loss of power/stalling may be related to an engine, fuel, oil pressure, electrical, ECM, or recall/service campaign issue. I am also concerned that the vehicle was low on oil despite regular oil maintenance and the oil life monitor still showing about 50%. The vehicle is currently at Tyrell Chevrolet for inspection/service. I have not yet received a clear explanation of the cause of the power loss, whether diagnostic trouble codes were found, whether oil pressure was affected, whether oil consumption was checked, whether any recall or service campaign caused or corrected the issue, or whether the truck is safe to drive. This sudden loss of power while driving at approximately 75 mph presents a serious safety risk and should be investigated. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11735307

Incident

Apr 24, 2026

The vehicle was shiifting sluggishly and the check engine light came on. The dealer has indicated that I need to replace a transmission controller valve body. This problem has been acknowledged by GM and a recall initiated, but my vehicle was not included in the recall. This does not seem reasonable and I believe the recall should be expanded.

NHTSA ID

11734849

Incident

Apr 18, 2026

On my 2021 Chevrolet Silverado 1500 Custom, I began noticing an issue around 79,000 miles where the vehicle did not come to a complete stop as smoothly as expected. Initially, I suspected the brakes, as I purchased the truck new and had not performed any brake maintenance up to that point. I scheduled an appointment with the dealership to have all four brakes replaced; however, upon inspection, I was advised that the brakes were still in good condition, with approximately 90% life remaining. I then completed a test drive with the shop foreman, who was able to replicate the concern to some extent and suggested that the issue may be related to the transmission. At this time, the dealership is in the process of disassembling the transmission to determine whether the issue can be resolved with a repair or if a full replacement is necessary. It is concerning that such a significant issue would arise at approximately 80,000 miles. Based on similar reports I have reviewed, this appears to be a relatively common concern within the 80,000–90,000 mile range. Additionally, this poses a serious safety concern, as the vehicle’s hesitation in coming to a complete stop nearly resulted in a rear-end collision while en route to the dealership. There have been no dash lights on.

NHTSA ID

11731041

Incident

Apr 13, 2026

I was accelerating to 45MPH on a main road. My truck was running just fine. At about 45 MPH it felt like I hit a wall, and my truck started to rapidly decelerate and seemed to be downshifting very hard. A reduced engine power warning appeared in the message display, and the check engine light illuminated and began to flash. I luckly the car behind me was able to change lanes quickly and missed me and I was able to pull off the main road and turn off the truck. I let it sit for five minutes and restarted the truck. When I did, the truck seemed to drive at 25 MPH, and I kept it at that speed and was able to get it to my work down the road. When I got to work, my company's mechanic ran the code. A P2732:00 Transmission control solenoid valve 6 stuck off and P0700:00 transmission control module requested MIL illumination codes came up. We also noticed my truck no longer went into reverse and the engine would just rev and nothing else happened. I had the truck towed to the Chevy dealer who also got a P2732 error code. The truck as been at the dealer for the last two weeks and I have not told them to fix it yet.

NHTSA ID

11730823

Incident

Mar 26, 2026

Rough shifting in low gears, can be dangerous in intersections due to low acceleration ability. The check engine light is on for replacement of Transmission Valve Body Assembly.

NHTSA ID

11730582

Incident

Apr 10, 2026

The transmission has been having issues for the past couple days. It is the 10 speed model and I have noticed everyday for the last couple days that there is an unusual shifting pattern between 25-60mph. This is sometimes accompanied with a shudder that feels like going over rumble strips without the sound. The feeling is not constant, but I will come to a complete stop and under light acceleration it will return. Under hard acceleration it is not noticeable. However, I am concerned with the unusual shifting. It can happen at a constant speed where it will do a random shift up or down or under light acceleration it will feel like it’s slipping for just a second. The vehicle has 99,900 miles on it and there are no warning signs or lights active. The vehicle is about to be serviced to do an inspection to find the underlying issue. This is a safety concern because the vehicle could potentially cause more damage to the transmission and with the random shifting, could potentially cause an accident.

NHTSA ID

11730045

Incident

Apr 8, 2026