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Engine & cooling

2021 Chevrolet Blazer Engine problems

Owners have filed 46 complaints about the 2021 Chevrolet Blazer's engine & cooling with NHTSA - 32% of all its complaints, most recently on November 4, 2026. They describe 0 crashes, 1 fire and 0 injuries. Stalling, loss of power, oil consumption, overheating, head gaskets, timing chains and engine failure.

Complaints
46
Recalls
0
Crashes
0
Fires
1
Injuries
0
Deaths
0

Engine complaints

Transmission & drivetrainEngine & cooling

On [[redacted]], my 2021 Chevy Blazer broke down in the middle of traffic in a left turn lane when it tried to auto-restart. I was left stranded for 2 hours and had to call the local police to direct traffic around me. Upon towing to a local auto shop, and then another two to Carl Black GMC in Roswell, Georgia, I learned that the engine had completely seized due to a leaking radiator. They quoted me $14,000 in repairs between the radiator and a new engine. The vehicle had approximately 84,000 miles at the time...

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and GM offered $3,000 to help with the engine. The car never threw a check engine light prior to the engine completely seizing. The coolant temperature gauge in the car also never showed temperatures above normal. At a few points, the car fan ran loud after turning the car off and I thought this might have been electrical. I sanded and cleaned the ground connection to the chassis which seemed to fix the issue. I also learned of Special Coverage N252508350-Engine Coolant Thermostat that was issued by GM which indicated this condition could be caused by a coolant engine thermostat that could open at a low temperature. I had planned to get it completed along with the fuel pump control module recall at my next opportunity. This issue with my car left my stranded in the middle of a busy highway with cars zooming around me. GM has known about the issue of leaking radiators in 2021 Chevrolet Blazers for years and has never done anything about it. Between their shoddy electrical systems and the radiator, these cars are of significant risk of seizing up in the middle of traffic with no warning like mine. GM has refused to replace these radiators or issue a recall becaus the repair is $2,000 and affects multiple lines of vehicles.

Filed Incident Power train · EngineNHTSA 11775638
Engine & cooling

My 2021 Chevy blazer is leaking oil at 70,000 miles Chevy only recalled under special warranty for camshaft carrier it appears Chevy put in a glue for them seals that comes off unfortunately they don't recall all blazers just some but I am having the same issue as that special warranty. It's a safety concern because no oil in the car can blow up the engine .6500 to repair

Filed Incident EngineNHTSA 11767069
BrakesEngine & cooling

Vehicle Information: 2021 Chevrolet Blazer 2.5L engine, VIN [[redacted]]. Odometer 118000 miles.Description of Incident: While operating the vehicle, the mechanical brake vacuum pump experienced a catastrophic internal failure. The drive gear housing shattered violently without warning, shearing off the end of the connecting engine camshaft. Because this was an instantaneous mechanical failure, the vehicles computer did not trigger any dashboard warning lights, check engine lights, or safe mode protocols prior to...

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the failure.Safety Hazards and Component Damage: First, the total destruction of the vacuum pump caused an immediate compromise to the brake booster vacuum lines, resulting in a sudden, dangerous loss of power braking assistance. Second, the sheared camshaft breached the engine valve cover or head, causing the engines pressurized oil system to instantly dump all engine oil externally onto the ground. Third, shrapnel or violent structural torque from the instant engine seizure punctured or severed the adjacent transmission cooler fluid lines and compromised brake fluid lines, causing total loss of transmission fluid and brake fluid simultaneously.Request for Action: This failure mirrors the exact mechanical defects documented in GM Technical Service Bulletin 21-NA-268 and previous GM vacuum pump recalls like NHTSA Recall 19V-645, which excluded the 2021 Blazer. I am filing this report because the lack of an electronic warning indicator before a catastrophic mechanical brake and engine failure poses an extreme, immediate threat to highway safety. GM must expand recall coverage or issue a Special Coverage Adjustment for this model year. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Incident Service brakes · EngineNHTSA 11764895
Wheels & tiresEngine & cooling

My 2021 Chevrolet Blazer has experienced repeated problems involving the cooling system and is now exhibiting recurring symptoms that concern me about the vehicle's reliability and safety. In 2023, the vehicle required a radiator/cooling-system repair. In 2024, it again required radiator/cooling-system repair, which was performed under warranty. The vehicle is now experiencing an abnormal humming/clicking noise from under the hood. The problem initially occurred primarily after rain but has become increasingly...

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frequent. When the noise occurs, the air-conditioning system stops cooling properly and blows warm air. The check-engine light has also illuminated intermittently. The exact component currently malfunctioning is unknown. The vehicle remains available for inspection. Because the symptoms involve the engine compartment and follow multiple previous cooling-system repairs, I am concerned about the possibility of overheating, loss of proper cooling-system operation, an unexpected breakdown while driving, or another mechanical failure that could place the occupants or other motorists at risk. Authorized Chevrolet dealerships previously inspected and repaired the vehicle's cooling system in 2023 and again in 2024. Despite those repairs, significant symptoms have returned. The current problem has not yet been definitively diagnosed, so I cannot state that the present failure is the same component previously repaired. The warning symptoms include the abnormal under-hood humming/clicking, loss of cold air from the air-conditioning system when the condition occurs, and an intermittent check-engine light. The symptoms have become more frequent over time. I am reporting this because of the recurring nature of the problem and the vehicle's history of multiple cooling-system repairs. I request that NHTSA document and evaluate this complaint together with any similar complaints involving this model and model year.

Filed Incident Wheels · EngineNHTSA 11764652
Engine & cooling

The contact owns a 2021 Chevrolet Blazer. The contact stated that a technician identified a radiator leak during an emissions test after smelling an abnormal coolant odor. The technician confirmed that the coolant had leaked from the vehicle. Prior to the discovery by the technician, the contact's husband observed white smoke coming from the engine. The fluid levels were checked and were normal at that time despite the smoke. Additionally, the contact stated that the message "Steering Assist Reduced" was displayed...

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on the instrument panel prior to the failure. The vehicle was not repaired. The dealer provided an estimate for the repair with 15% goodwill assistance towards the cost. The manufacturer was notified of the failure. The vehicle was not repaired. The failure mileage was 46,860.

Filed Incident Engine and engine coolingNHTSA 11763020
Engine & cooling

My 2021 Chevrolet Blazer RS equipped with the 3.6L LGX V6 experienced catastrophic engine failure at approximately 90,200 miles. The vehicle had no prior warning. The dealer diagnosed the timing chain / lift/ cam damage. I am requesting investigation into whether this represents a safety or durability defect affecting other vehicles

Filed Incident EngineNHTSA 11759058
Engine & coolingFuel system

Car will not crank, stalled while cranked, throws code P023F

Filed Incident Engine · Fuel / propulsion systemNHTSA 11758918
Engine & cooling

While idling in my driveway, the engine started to shake and the check engine light came on. Got it diagnosed and was told by a private repair center that we had lost compression in cylinder 4 and that it was not worth the repair and we needed to replace the engine. Got it towed to the dealership, Bill Fox Chevrolet, for a 2nd opinion and they confirmed what the private shop had said. Because the vehicle was well maintained with regular preventative maintenance, it was deemed the failure was not the fault of the...

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owner. GM extended a goodwill warranty to help cover the cost of the engine replacement (70% coverage. We were 1 month and 2,000 miles past our warranty). They never told us root cause, only that it would have cost more money to repair it than it would be to get a new engine. The Blazer had been running fine up to that point and was my wife's main mode of transportation. The Blazer only had 62,000 miles on it when the failure occured.

Filed Incident EngineNHTSA 11758482
Transmission & drivetrainEngine & cooling

The thermostat malfunctioned causing an error message regarding "steering assist is reduced". When I parked and turned off, the engine fan continued to run. When car was restarted, the temp gauge inside was stuck at C. Took to dealership and they assessed. They repaired the thermostat under power train warranty, however there was a crack in the radiator (top) resulting in the need for a new radiator. This vehicle had 35,000 miles on it. Upon research online, it seems there are MANY people who have had this...

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same issue and worse. It appears cars produced during COVID era are most affected. Chevy refused to warranty the issue. The dealership offered a small cost reduction (due to our loyalty). The thermostat and the radiator issues seem to be well known by Chevy, they just refuse to accept responsibility. Now we are out thousands of dollars on a basically "new" vehicle.

Filed Incident Power train · EngineNHTSA 11745926
Electrical systemEngine & coolingDriver assistance

The thermometer and thermometer sensor are glitching . The engine temp needle will not rise at all, the engine fan will run the whole time driving and then when it is turned off will run for 10 min . Right before this happens a notice shows the guided steering is being limited. I disconnected the battery and it reset , I drove and there were no issues , next time I started my car the engine temp needle stayed down and the van started again. This car has 36k miles on it. I just bought it 2 days before it started happening

Filed Incident Electrical system · Engine · Lane departureNHTSA 11745573
BrakesEngine & coolingFuel system

Went to park car in a park to drop daughter off and it sputtered out and stalled out of nowhere with no warning. I had received a lamp warning very sporadically prior to this and on occasion that stated 'reduced steering assist drive with care' this resulted in heavy steering for that drive until car was shut off and then it would go away and be fine again, fixed the car through Knudtsen Chevy due to a recall about a month before on the issue with the engine being turned off and it thinking it was still hot and...

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still running the fan (even though the car was not running). Knudtsen fixed that issue. Low battery voltage light did not come on however battery was older so had battery installed at park to ensure the issue was not due to the battery. The oil was fresh and showed no issues, changed 2 weeks before fresh oil no issues found during service. When tried to restart the car it would think it would try to start and then sputter out and not stay in idle. Les Schwab left and called a mobile mechanic to bring the computer. Computer was hooked up and it would try to start, however, it would not know it was already running and try to start again on it's own...the codes that came up were the PO101 code came up for Mass Air Flow issue...and then the codes would go in a wild sequence of fail.....mechanic checked for loose connections around air filter, took air filter out and it was clean no issues, checked pipe no visible issues. We walked away and walked around the park to give it some time to sit and then we tried it again and it tried and sputtered out and died again would not stay idling. Then all of a sudden we heard it try to start itself without us trying to start it and it clanked. We hauled it to Knudtsen for a diagnosis. They stated "the motor will not turn this way or that way and it is seized or locked up". This is a 2021 with only 89,000 miles it should have a longer life than this. Please investigate and is there anything we can do to fix it?

Filed Incident Service brakes · Engine · Fuel / propulsion systemNHTSA 11734510
Engine & cooling

Both camshaft carriers failed due to a manufacturing defect. According to NHTSA bulletins 21-NA-240 and PIP5755, the oil leak from the cam carrier is caused by improper sealant application during manufacturing. Although the dealer addressed the issue, it was clearly not a problem that arose from normal use. The leak had the potential to worsen and lead to a fire hazard. Chevy of Montebello confirmed the issue and repaired the vehicle for over $7,500. There were no warning signs, as the leak was difficult to detect on the driveway. The low-oil warning light came on the day before we took the vehicle to the dealer.

Filed Incident EngineNHTSA 11734437
Engine & cooling

The vehicle had an oil leak from both the left and right camshaft carriers. The dealer confirmed the issue and carried out the necessary repairs. Because the leak was not easily detectable, it could have led to engine failure while driving. There were no warning indicators; only small oil droplets were found on the ground.

Filed Incident EngineNHTSA 11731606
Transmission & drivetrainElectrical systemEngine & cooling

Once I turn the vehicle off, there is a loud sound coming from the engine area that sounds like a fan. Then the first incident of the fan ongoing after the vehicle was powered off, a battery light was on the internal driver dashboard and stayed on. The battery was recently replaced during 2026 so the battery should not be anywhere near dead, dying, or needing to be checked

Filed Incident Power train · Electrical system · EngineNHTSA 11730609
Engine & cooling

Coolant smell when parked with engine running. Radiator was replaced under warranty at 16,000 miles Coolant smell again 49,000 miles. "Pressure tested at dealership with following notes: "Found radiator core on driver side seeping/leaking. provided estimate on cost. no repair made during this visit." Many forums on 2021 Chevrolet Blazer note poor quality in radiators. This would be the 3rd radiator in less than 50,000 miles on the vehicle.

Filed Incident EngineNHTSA 11723904
Transmission & drivetrainElectrical systemEngine & cooling

This submission is an additional report related to NHTSA complaint #11714381. At approximately 55,000 miles, my 2021 Chevrolet Blazer experienced a sudden throttle body failure while driving. The vehicle entered reduced engine power/limp mode without warning and acceleration was significantly limited. This created a safety concern while driving in traffic, particularly when merging and crossing intersections. Diagnostic code P2101 (Throttle Actuator Position Performance) was present. A Chevrolet dealer confirmed...

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an internal throttle body failure and replaced the throttle body assembly. Although the repair was completed, this failure occurred at relatively low mileage for a critical engine control component. A sudden loss of acceleration can pose a safety risk depending on traffic conditions. Since filing my original complaint, I have identified multiple similar reports online and in owner forums describing premature throttle body failures in GM vehicles with similar symptoms (reduced power/limp mode and limited acceleration). This suggests the possibility of a broader pattern involving this component. I am submitting this additional report so that NHTSA has a complete record of the incident and potential pattern of premature throttle body failures. If this issue is widespread, it may warrant further review or investigation as it affects vehicle acceleration and safe operation.

Filed Incident Power train · Electrical system · EngineNHTSA 11719088
Engine & cooling

The 2021 GMC Blazer (and related Chevy Blazer models) is experiencing recurring radiator failures, often requiring multiple replacements within short timeframes. The radiator was replaced in March 2024 and in early 2025 I went for an oil change and complained of smelling coolant and asked if it could be checked and was told nothing was wrong. I was told again in November 2025 that it has a leak and went to have an oil change in February 7, 2026 and was reminded that the coolant was low and the radiator needs replacing when I was first told I did not believe it to be true as it has been replaced before and I asked that it be checked and was told nothing was wrong.

Filed Incident EngineNHTSA 11716656
Transmission & drivetrainElectrical systemEngine & cooling

Around 55,000 miles, my 2021 Chevrolet Blazer experienced a throttle body failure. The check engine light illuminated and the vehicle entered a reduced power/limp mode condition. Throttle response was significantly limited, and the vehicle could not accelerate normally. While the vehicle remained drivable, it took substantially longer to reach speed, which could pose a safety risk when merging into traffic or crossing intersections. Diagnostic trouble code P2101 (Throttle Actuator Position Performance) was...

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present. A Chevrolet dealer confirmed an internal throttle body failure and replaced the throttle body assembly. This component is a critical engine control system, and failure could affect acceleration and vehicle control, posing a potential safety risk. The failure occurred well before expected service life and required a costly repair. The component has been replaced and is available for inspection upon request. I believe this may represent a premature defect and should be investigated for similar failures in other vehicles.?

Filed Incident Power train · Electrical system · EngineNHTSA 11714381
Engine & cooling

Radiator failure caused power steering assist to not function properly and insufficient vehicle heat function. Engine electric fan would run continuously after vehicle shutdown.

Filed Incident EngineNHTSA 11707571
Transmission & drivetrainAcceleration & cruise controlEngine & cooling

For about a week and a half my car had made a high pitched wheezing/hubbing sound when started cold. This occurred at all temperatures cold and warm. Yesterday December 13th I went to run some errands and about a mile into my drive my 2021 3lt 3.6 V6 Chevrolet Blazer lost the ability to power itself. There was no electrical problem however the power train lost power all gears drive and reverse. I was able to get off the roadway without incident. I scan my check engine light and had several check engine lights including a P 0796.

Filed Incident Power train · Vehicle speed control · EngineNHTSA 11705228
Transmission & drivetrainEngine & cooling

My 2021 Chevrolet Blazer experienced a radiator failure at approximately 42,000 miles. The radiator and cooling system malfunctioned, causing coolant loss and triggering a warning light on the instrument panel. The failed radiator is available for inspection upon request. This defect put my safety and the safety of others at risk because a compromised radiator can lead to engine overheating, sudden loss of power, or even steering assist reduction while driving. These conditions increase the likelihood of an...

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accident, particularly at highway speeds. The problem was confirmed by my Chevrolet dealer, who diagnosed the radiator as needing replacement. They initially quoted $1,800, later reducing the cost to $915.90 after acknowledging that approximately 20 customers per month at their dealership alone are experiencing the same issue. This indicates the defect is widespread, at least regionally, and may be systemic across the model. The vehicle has been inspected by the dealer service department, which is an authorized GM representative. No police or insurance inspection has occurred. Prior to the failure, a warning lamp illuminated on the instrument panel, alerting me to a cooling system issue. This was the first symptom I noticed before bringing the vehicle in for service. I believe this premature radiator failure represents a systemic defect in the 2021 Chevrolet Blazer's cooling system. It occurred well within the 5-year/60,000-mile warranty period, yet the dealer claimed the radiator is not covered. I am requesting NHTSA investigate this issue, as it appears to affect many owners and poses a significant safety risk.

Filed Incident Power train · Unknown or other · EngineNHTSA 11703542
SteeringEngine & cooling

In September 2023, when getting my vehicle serviced for a routine oil change, I was told there was a leak in my radiator. They replaced the entire thing under warranty. On November 15th, 2025, while driving on the highway heading home from out of town with my children, an error flashed up saying "steering assist is reduced - drive with care" Upon arriving home, the fan on my car was running on high for a solid 10 minutes after turning the car off. No recall but Special Coverage N252508350 covers the thermostat...

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replacement. Upon inspection by a mechanic, I was informed that the radiator is also leaking again in the exact same spot as it was previously. It should be noted I have never seen leaking fluid in my garage/driveway. I've driven less than 10,000 miles since the radiator was replaced previously. If there is a known problem with the coolant system which can cause overheating and steering assist issues, why isn't the faulty radiator and thermostat recalled. The radiator is cased in plastic to aluminum. Plastic can easily catch fire if a car overheats. The casing also prevents an owner from even knowing if there is a leak since the plastic is catching leaks - the mechanic informed me that's why I didn't know about both times it leaked. This is a 4yr old car with 46k miles, twice replaced radiator and thermostat. A recall should be issued since both problems could potentially cause a fire from an overheated engine & loss of steering assist while driving. A google search quickly showed me thousands of other Chevy Blazers from 2019-2021 with reoccurring thermostat and radiator issues. I feel unsafe driving in my vehicle but still owe too much to even trade it in for something else. I've owned dozens of vehicles in my lifetime, used and new and keep them 8-10yrs and have never had to replace a thermostat and radiator. This vehicle is dangerous due to GM/Chevy's cheap radiator model and thermostat which could overheat and catch fire

Filed Incident Steering · EngineNHTSA 11701205
Electrical systemEngine & coolingFuel system

Car was running fine yesterday, today does not want to start. Thought it was the battery, bought anew battery. Still wouldn't start. Rest of cat is getting great power. Code reader is reading its a fuel pump control moduler which just so happens to be in an open recall for my exact year of vehicle yet my vin number does not pop up on the GMC website under active recall. I have a 2021 chevy blazer .

Filed Incident Electrical system · Engine · Fuel / propulsion systemNHTSA 11699684
Electrical systemEngine & cooling

Action Required "Steering Assist Warning" drive with caution, Temp gage reads cold, A/C stops working, engine cooling fan runs on high speed (even after the engine is shut off), pending P2018 code, with no Check Engine Light (CEL). Replaced Engine coolant Temperature (ECT) sensor, problem did not go away. Several reviews suggest to replace the thermostat, check fuses for proper insertion, reroute ECT wiring, and possibly replace radiator. Most of these repairs can be very expensive. Chevy Blazer Forum states that the issue is a out of range detection of ECT sensor reading. GM needs to determine a true solution and stop guessing at owner expense/frustration.

Filed Incident Electrical system · EngineNHTSA 11697313
Engine & cooling

Radiator leak, leaking antifreeze

Filed Incident EngineNHTSA 11689652

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Source: U.S. National Highway Traffic Safety Administration (NHTSA) complaints and recalls, checked . Complaints are owners' own reports and are not verified. How we use the data

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