This preliminary informational (PI) bulletin provides information to dealership personnel that may be helpful when addressing underbody component corrosion with customers.
full bulletin at NHTSA ↗2021 Chevrolet Blazer powertrain problems
moderate 13 complaints filed with NHTSA · avg repair $2,500 · see powertrain across all vehicles →
Complaints
13
Recalls
0
Avg fix
$2,500
When does it fail?
Of the 13 powertrain complaints filed for the 2021 Chevrolet Blazer, here's the actual mileage breakdown — failures cluster heaviest at 25,000-50,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Among the 6 model years of Chevrolet Blazer in our records for powertrain problems, this one ranks #3 by owner-complaint volume.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This bulletin provides information on identifying Non-GM Engine Calibrations for Gasoline Engines using the Tech 2 or GDS 2.
full bulletin at NHTSA ↗This service bulletin provides information on the harmful effects of ethylene glycol in transmission fluid.
full bulletin at NHTSA ↗This service bulletin provides 9th gear operation information to respond to customers that may comment on transmission shift operation.
full bulletin at NHTSA ↗This service bulletin advises the tech that the rotational Clicking Noise Heard After Engine Shut Down may be normal characteristics of the vehicle.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners report powertrain failures across multiple systems in 2021 Chevy Blazers between 28,000 and 90,000 miles. Radiators fail prematurely and lose coolant; one dealer acknowledged ~20 customers per month experiencing this, with a service bulletin confirming supplier quality issues. Throttle bodies fail identically in two separate vehicles at 55,000 miles, both pulling diagnostic code P2101 and forcing limp mode, limiting acceleration dangerously in traffic. Transmissions develop multiple failure modes: delayed and harsh reverse engagement progressing to complete reverse loss, sudden neutral-like conditions with high revs but no drive, metal fragments in fluid, and intermittent jerking that recurs after dealer repairs. One vehicle stalls unpredictably during turns starting at 28,000 miles without warning lights, confounding dealer diagnosis. A fuel pump failure triggered P023F at 90,493 miles. Thermostats stick open, causing cooling fans to run after shutdown and draining batteries; a service bulletin exists for this. One vehicle produced wheezing cold-start noise before losing all powertrain power. Dealers report encountering these same issues repeatedly, yet some deny warranty coverage despite failures occurring well within the 5-year/60,000-mile window. No clear single root cause emerges; the breadth and consistency of failures suggest systemic quality issues across multiple powertrain subsystems.
Same Chevrolet Blazer powertrain reports on nearby years: 2019 · 2020
Failure modes owners describe
Radiator Failure
Radiator develops coolant loss and fails, triggering cooling system warning lights. Multiple owners report premature radiator failure at relatively low mileage. One dealer noted approximately 20 customers per month experiencing the same issue. A service bulletin acknowledges radiators can fail due to poor quality from supplier, with some replaced under warranty and others denied.
When: 42,000 miles to 47,000 miles
Symptoms owners cite: Coolant loss; Cooling system warning light illuminated; Vehicle running hot
Repairs/costs cited: Radiator replacement; dealer quoted $1,800 initially, reduced to $915.90 after acknowledging systemic issue
Recalls/TSBs owners mention: Service bulletin exists regarding radiator failure due to supplier quality issues; some replacements covered under warranty, others denied despite being within 5-year/60,000-mile coverage period
Throttle Body Failure
Throttle body fails internally, causing the vehicle to enter reduced engine power/limp mode. Engine control component loses ability to modulate throttle position, severely limiting acceleration. Two owners report identical failures at nearly the same mileage with the same diagnostic code. Owner research identified multiple similar reports in owner forums suggesting a broader pattern.
When: 55,000 miles
Symptoms owners cite: Reduced engine power/limp mode; Limited acceleration; Check engine light illuminated; Sluggish throttle response
Codes mentioned: P2101 (Throttle Actuator Position Performance)
Repairs/costs cited: Throttle body assembly replacement required
Transmission Reverse Failure
Transmission develops delayed engagement when shifting into reverse, progressing to harsh engagement, and eventually complete loss of reverse. Vehicle will not move when shifted into reverse, creating a safety issue for parking and maneuvering.
When: 89,000 miles
Symptoms owners cite: Delay when shifting into reverse; Harsh engagement into reverse; Complete loss of reverse function; Vehicle will not move in reverse
Repairs/costs cited: Transmission failure diagnosed; repair not completed as of complaint submission
Transmission Loss of Power/Neutral Condition
Transmission enters a neutral-like condition where the vehicle will not engage in any gear. Engine revs but vehicle does not move. In one case accompanied by metal fragments found inside transmission fluid, indicating internal transmission damage. Owners report transmission shudder during acceleration prior to complete failure.
When: 84,000 to 90,000+ miles
Symptoms owners cite: Vehicle operates as if in neutral; High RPMs with no power transfer to wheels; Vehicle stalls and slows down; Will not engage in drive or reverse; Transmission shudder during acceleration from 0-40 mph; Abnormal roaring sound from engine compartment
Codes mentioned: P0796
Repairs/costs cited: Entire transmission system replacement required; metal fragments found in transmission fluid
Recalls/TSBs owners mention: Manufacturer case opened; vehicle not repaired as of complaint submission
Engine Stalling During Turns
Vehicle stalls intermittently while making turns, particularly left turns, at low speeds. Engine stalls while accelerating or turning at traffic speeds. Failure occurs without warning lights and cannot be reproduced by dealer, making diagnosis difficult.
When: 28,000 miles
Symptoms owners cite: Vehicle stalls during left turns at 10 MPH; Vehicle stalls during left turn at green light; Intermittent stalling while driving and turning; Only rear tires would move (mentioned once)
Repairs/costs cited: Dealer unable to diagnose or duplicate failure
Recalls/TSBs owners mention: Manufacturer case opened; no resolution identified
Fuel Pump Failure
Fuel pump fails, triggering a service engine warning and limiting vehicle operation. Diagnostic code points to electrical pathway issue supplying power to the fuel pump. Vehicle required towing for diagnosis and repair.
When: 90,493 miles
Symptoms owners cite: Service Engine Soon message displayed; Vehicle unable to operate normally
Codes mentioned: P023F (Powertrain Control Module Detected a problem in the Electrical Pathway supplying power to the Fuel Pump)
Repairs/costs cited: Fuel pump replacement required; independent mechanic diagnosed failure
Recalls/TSBs owners mention: Recall number N252516900 mentioned by owner, though VIN not included; manufacturer not made aware per owner statement
Thermostat Malfunction with Cooling Fan Issue
Thermostat sticks open, causing cooling system malfunction. Engine cooling fans continue running after vehicle is powered off, draining battery. Service bulletin exists acknowledging this issue and extending warranty coverage. Multiple owners report this intermittent problem.
When: 47,000+ miles
Symptoms owners cite: Cooling fan runs continuously after vehicle is turned off; Thermostat sticks open; Battery light illuminated on dashboard; Steering assist reduced warning with engine light; AC does not work during thermostat malfunction
Repairs/costs cited: Thermostat replacement required
Recalls/TSBs owners mention: Service bulletin extends warranty coverage for thermostat malfunction and cooling fan running after vehicle is off
Cold Start Engine Noise with Subsequent Power Loss
Vehicle produces high-pitched wheezing or humming noise when started in cold conditions. Within a week of this noise occurring, powertrain suddenly loses all power in all gears (drive and reverse), leaving vehicle immobilized with no electrical problems evident.
When: No mileage stated; event occurred after cold-start noise persisted for one week
Symptoms owners cite: High-pitched wheezing or humming sound on cold start; Noise occurs at all temperatures; Sudden loss of powertrain power in all gears; Drive and reverse gears non-functional
Codes mentioned: P0796
Repairs/costs cited: No repair completed as of complaint submission
Transmission Jerking and Stopping
Transmission jerks and causes vehicle to stop intermittently during normal driving. Problem recurs despite multiple dealer repair attempts. Owner suspects transmission defect affecting multiple vehicles of the same model.
When: 82,000 miles at complaint filing; purchased used in 2024
Symptoms owners cite: Vehicle jerks and stops while driving; Intermittent transmission issue; Problem recurs after repair attempts
Repairs/costs cited: Multiple dealer repair attempts; dealer claimed to fix but issue recurred months later
Recalls/TSBs owners mention: Possible recalls exist per owner statement, but owner unsure if their vehicle is covered
Synthesized from 13 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 4 most recent
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…
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,…
The contact owns a 2021 Chevrolet Blazer. The contact stated that while driving approximately 10 MPH and attempting to make a left turn, the vehicle stalled. The contact depressed the accelerator pedal aggressively several times to get the vehicle to start moving again. The failure reoccurred while the contact’s daughter was driving and attempting to make a left turn at a green light when the…
I purchased my 21 Chevy blazer in 2024 and had a few problems with a transmission problem. The vehicle would stop and jerk whenever I drove it. I took it to the dealer a few times for repair. They claimed to have fixed the problem, but it started again several months later. The vehicle has approx 82,000 miles on it. I heard that there were some recalls on these vehicles, but not sure if mine is…
Had powertrain trouble with your 2021 Chevrolet Blazer?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the powertrain problem on the 2021 Chevrolet Blazer?
It's a documented issue but not catastrophic. 13 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain typically fail?
Based on the 13 complaints filed, powertrain issues most often appear around 67,498 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $2,500 for powertrain repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to powertrain?
No active recalls currently cover powertrain issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2021/Chevrolet/Blazer.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.