This service bulletin provides information on replacing the intake manifold when the engine is replaced after severe internal engine damage.
full bulletin at NHTSA ↗2020 Chevrolet Blazer engine problems
moderate 31 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
31
Recalls
0
Avg fix
$3,100
What stands out
Of the 6 model years of Chevrolet Blazer we track for engine problems, this one carries the most owner complaints on file — 31.
Owners have filed 31 engine complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering engine 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.
The service bulletin advises the tech of a normal transmission shift condition and the delay in throttle response when the throttle plate is opened rapidly and advises the customer that it is normal for the delay.
full bulletin at NHTSA ↗This service bulletin provides information to dealership personnel for new vehicles with less than 1,000 miles that may not pass California smog inspection or smog inspection in other states.
full bulletin at NHTSA ↗This service bulletin provides diagnostic repair information to correct an oil leak in the engine.
full bulletin at NHTSA ↗This service bulletin provides a procedure to test and replace the battery distribution fuse block if found the cause of the DTC and electric coolant pump inoperative.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2020 Chevy Blazer exhibits a widespread thermostat malfunction that affects multiple vehicles between 15,000 and 97,000 miles, with many failures occurring before 60,000 miles. When the thermostat sticks open or closed, the temperature gauge locks at cold, the engine cooling fan runs continuously at high speed, the check engine light illuminates with code P0128, and—most critically—the steering assist warning appears and power steering assistance cuts off. A/C stops working or blows only warm air. Multiple owners report these problems are documented in Chevrolet service departments as "known issues," yet GM refuses to issue a recall or technical service bulletin.
Radiators also fail prematurely, with replacements required as early as 16,000 miles; one owner had to replace the radiator three times. The thermostat housing sits under the intake manifold, making repairs labor-intensive and costly—$600 to $1,400 reported. Even worse, owners report the same failures returning 1,800 miles after initial repair, suggesting the root cause goes unaddressed. Oil leaks from camshaft housing gaskets and transmission seals compound reliability concerns. Owners emphasize the safety risk: a vehicle that randomly disables steering assist at highway speeds while simultaneously overheating creates genuine hazard. Warranty expirations around 60,000 miles leave owners paying full freight despite the manufacturer's awareness of these defects.
Same Chevrolet Blazer engine reports on nearby years: 2021
Failure modes owners describe
Thermostat stuck open or closed
Thermostat fails to regulate coolant temperature properly, locking in either extreme cold or hot position. This is reported as a widespread, documented issue affecting multiple 2020 Blazers with the 3.6L engine.
When: Occurs between 15,000 and 97,000 miles; multiple complaints cite failures before 60,000 miles; one failure at 52,377 miles; one at 19,900 miles.
Symptoms owners cite: Temperature gauge stuck on cold or not functioning; Check engine light illuminates; Steering assist reduced warning appears on dash; A/C disabled or blows warm air; Engine cooling fan runs continuously at high speed; Vehicle shuddering when driving uphill; Engine may overheat, creating fire risk; Recurring issues even after repair
Codes mentioned: P0128 (coolant thermostat system malfunction)
Repairs/costs cited: Complete thermostat replacement cost reported at $600 to $1,400 labor plus parts. Thermostat housing replacement cited. One case required removal of intake manifold, increasing labor complexity and cost. Repairs often fail to resolve the issue long-term; one owner reported the same problem returning 1,800 miles after initial thermostat and sensor replacement.
Recalls/TSBs owners mention: GM has acknowledged this as a known issue in service departments but has not issued a recall or technical service bulletin. Owners with expired powertrain warranty are being required to pay full repair costs out of pocket. Two dealerships (Serra Chevrolet and others) confirmed to owners this is a documented problem.
Radiator leaking or cracked
Radiator seals fail prematurely, causing coolant leaks. Owners report this occurs across the model year and is linked to thermostat failures due to improper cooling.
When: Radiator leaks reported at 16,000 miles (first replacement), 19,900 miles, and under 60,000 miles; one owner had to replace three times over vehicle ownership.
Symptoms owners cite: Coolant leaking visible under vehicle; Engine overheating; Vehicle stranded on highway due to overheating; Risk of engine fire
Repairs/costs cited: One owner replaced radiator three times since ownership. Radiator replacement occurred at 16,000 miles for one complaint; multiple owners report replacements well under 60,000 miles, which is premature for a vehicle at that price point.
Recalls/TSBs owners mention: No recall or warranty extension mentioned. Owners note this should be covered but are paying out of pocket.
Coolant temperature sensor failure
Temperature sensor malfunctions in conjunction with thermostat failure, sending incorrect signals to the engine control unit and disabling safety features.
When: Occurs in conjunction with thermostat failures between 15,000 and 97,000 miles.
Symptoms owners cite: Temperature gauge reads zero or cold constantly; Steering assist disabled; Check engine light; A/C inoperable
Codes mentioned: P0128
Repairs/costs cited: Replaced alongside thermostat; cost included in thermostat repair estimates of $600–$1,400. Replacement often ineffective; problem recurs.
Steering assist disabled (secondary to thermostat failure)
Power steering assist warning appears and steering assist cuts off, likely due to engine control module failsafes triggered by coolant system faults. Creates serious safety hazard during highway driving.
When: Occurs when thermostat and coolant sensor fail; timing correlates with temperature fluctuations and cold weather in some cases.
Symptoms owners cite: Steering assist reduced warning message on dash; Power steering assist cuts off while driving; Vehicle may enter limp mode at highway speeds (70 mph reported); Creates uncertainty about vehicle handling and safety
Repairs/costs cited: Does not require separate repair; resolves if thermostat is corrected, but problem persists in many cases despite repair attempts.
Recalls/TSBs owners mention: No recall or technical service bulletin issued despite widespread reports.
A/C inoperative
Air conditioning stops functioning when thermostat and coolant sensor fail, as the engine control module disables non-essential systems in response to coolant anomalies.
When: Occurs during thermostat failure events; summer temperatures reported to worsen the issue.
Symptoms owners cite: A/C blows warm air or does not blow at all; Loss of heating in winter
Repairs/costs cited: Resolves when thermostat is replaced, but problem recurs if thermostat fix fails.
Air flow shutter damage
Coolant system failure and resulting thermal cycling damages the vehicle's air flow shutters, compounding cooling system problems.
When: Occurred approximately 1,800 miles after initial thermostat and sensor replacement (total mileage 97,000).
Symptoms owners cite: Check engine light illuminates again after repair
Repairs/costs cited: Requires replacement; not repaired in the complaint narrative (contact referred to NHTSA).
Recalls/TSBs owners mention: Manufacturer aware but no recall issued.
Radiator leak due to seal failure
Radiator seams leak coolant due to manufacturing or material defect, exacerbating the thermostat and sensor issues.
When: At 19,900 miles; also reported at 16,000 miles in a separate case.
Symptoms owners cite: Coolant seeping from radiator seams; Vehicle unreliable due to overheating risk
Repairs/costs cited: One owner replaced radiator three times over vehicle ownership.
Recalls/TSBs owners mention: Noted as known issue in forums but no recall.
Oil leaks from camshaft housing gaskets or transmission seal
Multiple oil leaks reported, some from camshaft housing gaskets, others from transmission seals. Suggests systemic gasket/seal quality issues on the 3.6L platform.
When: Reported at various mileages; one case at purchase (lightly driven, low miles); another requiring extensive repair at higher mileage.
Symptoms owners cite: Oil pooling under vehicle; Repeated oil leaks from same or different locations
Repairs/costs cited: Camshaft housing gasket replacement is extensive, requiring weeks of work. Transmission seal leak requires dealer service. One owner paid out of pocket for first repair, then faced second leak shortly after.
Recalls/TSBs owners mention: One similar recall on same year/model mentioned by owner, but their vehicle not listed.
Synthesized from 31 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 6 most recent
Radiator was found to be leaking. Now thermostat is sticking. This could have caused my engine to overheat and catch fire. I have had a mechanical shop replace the radiator but could not afford to replace the thermostat yet. I had been seeing warning lights and still see warnings after radiator was replaced. They said “Steering Assist Reduced” and “ESC” and the engine light came on. I went to…
The thermostat failed on a trip locking in 0 temperature reading and steering assist warning. Licensed mechanic repaired on 10/9/25 invoice is available. 67,509 miles. This could risk overheating and destroying the engine and might cause accident. Two other friends have had similar issues, appears to be a safety defect!
Thermostat/thermostat sensor and complete water outlet system replacement at only 52,377 miles. The defective part was located under the Intake Manifold requiring its removal, excessive labor cost for the repair, and potential future engine issues due to exposed/open head gasket for the repair.
Steering assist warning and engine check light are on. I had an scan done and was told it was the thermostat and coolant temperature sensor which seems to be a common problem. There are no safety concerns to my knowledge. I feel this problem needs to be addressed as repairs are very costly.
The car repeatedly has an error pop up that states steering assist is no longer activated and to drive with caution. The thermostat during this is also fully on cold. The check engine comes on after. The sensor and thermostat are repaired based on the code and problem persists. Same problem all over forums but Chevy refuses to fix as no recall. This is very concerning as the car may randomly go…
The 2020 blazer is having the same coolant temperature problem the 2021 blazer has and the recall needs to be expanded. Thermostat messed up, constantly losing coolant, check engine light, steering reduced
Had engine trouble with your 2020 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 engine problem on the 2020 Chevrolet Blazer?
It's a documented issue but not catastrophic. 31 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Based on the 31 complaints filed, engine issues most often appear around 56,000 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 $3,100 for engine 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 engine?
No active recalls currently cover engine 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/2020/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.