2020 Chevrolet Blazer Problems

What owners report

Owners of the 2020 Chevrolet Blazer most often describe a cluster of related cooling-system symptoms: a P0128 code, a temperature gauge that stays cold, cooling fans running at full speed, loss of A/C, and a "Steering Assist Reduced" message, typically followed by a check engine light. A second frequent theme is the "Shift to Park" message appearing while the shifter is already in park, which can prevent the vehicle from shutting off. Reports span from very low mileage to well over 100,000 miles, and many owners say the same repair (thermostat replacement) has been attempted more than once.

1. 1
   Engine

   Thermostat failure with reduced steering assist and A/C loss

   • 117 complaints (52%)
   • median 54,483 mi at 5.7 yrs old (15 state mileage)
   • 1 mention a crash, fire or injury
   • owner-quoted repair $1,308 (median of 16 quotes)
   • filed 2021–2026

   Owners describe a check engine light with code P0128, a temperature gauge that sits at the cold mark, radiator fans running on high, and the heater or A/C blowing hot or not cooling. Along with this, a "Steering Assist Reduced - Drive with Care" message appears and steering can feel stiffer. Complaints say dealers diagnosed a failed thermostat or temperature sensor; several owners report the same symptoms returning after replacement, and one was quoted roughly $1,100 for the repair. Reported from a few thousand miles up to about 100,000 miles, with many descriptions clustered in the 40,000-70,000 mile range.

   1 related service bulletin

   What to check: Scan for stored or pending P0128 and check whether the thermostat, coolant temperature sensor, and water outlet have already been replaced. During a test drive, confirm the temperature gauge rises to normal, the fans cycle off, and no steering assist message appears.

   2 excerpts from owner complaints in NHTSA records

   “P0128 code produced when scanned. Cooling fans on high. No ac. Steering Assist Warning. Had to replace the thermostat. ECM also replaced and caused the tire pressure sensors to fail and had to replace the tire sensors. There is a recall on models 2021 to 2025 but none on the 2020 for the thermostat. I have paid $3500.00 to have my vehicle fixed.”

   NHTSA complaint #11738607, filed 2026-05

   “I have had to replace the radiator 3 times since I've owned this vehicle. I see where there are others with the same issue. Now I have to replace the thermostat my first radiator was replaced at 16k miles. This is a safety issue because my car over heated and broke down on the highway left me stranded”

   NHTSA complaint #11655633, filed 2025-04
2. 2
   Transmission and drivetrain

   "Shift to Park" message with shifter already in park

   • 72 complaints (32%)
   • median 49,000 mi at 5.3 yrs old (11 state mileage)
   • 2 mention a crash, fire or injury
   • owner-quoted repair $1,100 (median of 8 quotes)
   • filed 2020–2026

   Owners report that after shifting into park, the vehicle displays "Shift to Park" and will not fully power down, leaving the radio and lights on or sounding chimes. Some describe having to cycle through drive and back to park several times before it registers, and a few say the vehicle rolled or moved when they believed it was parked. Complaints mention dealer diagnosis of a failed shifter assembly or park switch, and some owners refer to a service bulletin covering the symptom. Reported from around 8,000 miles up to about 128,000 miles, with many cases in the 20,000-80,000 mile range.

   1 related service bulletin

   What to check: Put the vehicle in park, shut it off, and confirm the message does not appear and everything powers down. Ask whether the shifter assembly or park switch has been replaced, and always use the parking brake as a backstop.

   2 excerpts from owner complaints in NHTSA records

   “I am experiencing the well known shift to park message while the shifter is in park. I cannot turn the vehicle off and I am worried the battery will die. This is a well documented issue with this vehicle, and several other models outlined in TSB 19-NA-206, for years and yet they refuse to issue a recall to repair the faulty design or component . I have reached out to them via email, but no action has been taken, see email below. …”

   NHTSA complaint #11672407, filed 2025-07

   “The car is not sensing that it is in park when it is. When I place it in park and turn the car off it dings and says shift into park however it already is in park. Therefore the car will not turn off. I had to jiggle the shift or turn the car on, reverse then go forward then park to get it to register. This has taken up to 10 minutes and it’s getting worse. This is a known issue that is referenced in GM Technical Service Bulletin 19-NA-206.”

   NHTSA complaint #11758760, filed 2026-08
3. 3
   Transmission and drivetrain

   Transmission hesitation, slipping, and shudder

   • 34 complaints (15%)
   • median 63,670 mi at 5.1 yrs old (10 state mileage)
   • 2 mention a crash, fire or injury
   • filed 2020–2026

   Complaints describe the transmission slipping or hesitating in lower gears, jerking when accelerating from a stop, and on some occasions failing to move in gear. A few owners report the vehicle lunging forward or rolling after being shifted, and some say the dealer diagnosed a powertrain or shifter-related failure. Owners also describe low-speed shudder and shake, which service information addresses as a fluid condition. Reported from about 1,500 miles to over 150,000 miles, with many cases around 45,000-80,000 miles.

   Recall 20V6680002 related service bulletins

   What to check: Test-drive from a cold start through several stop-and-go cycles and feel for shudder, slipping, or delayed engagement. Ask whether the transmission fluid service described in the low-speed shudder bulletin has been performed.

   2 excerpts from owner complaints in NHTSA records

   “With approximately 1500 miles on the vehicle, the Blazer's automatic transmission failed while driving. I was stopped at a red light. When the light turned green, I proceeded slowly through the intersection in a left turn. As soon as I left the intersection, just as the vehicle would typically up-shift, the RPM spiked, the vehicle jolted forward, and the check engine light came on. After the initial jolt, the vehicle would not shift out of first gear. I found a safe place to park and stopped the engine. …”

   NHTSA complaint #11343879, filed 2020-08, 1,500 miles

   “The contact owns a 2020 Chevrolet Blazer. The contact stated that while driving at an undisclosed speed, the vehicle hesitated with a grinding sound coming from the vehicle, with the check engine warning light illuminated. The contact stated that the vehicle was jerking while driving and while accelerating from a stop. In addition, the contact noticed fuel leaking from the front end of the vehicle while the vehicle was parked at the residence. …”

   NHTSA complaint #11704538, filed 2025-12, 157,236 miles
4. 4
   Electrical system

   Stalling, no-start, and electrical/display dropouts

   Mentioned in 6 of 60 sampled complaints

   Owners describe the engine cutting out while driving, intermittent no-crank or no-start conditions, and the instrument cluster going dark before a stall. Some report the infotainment screen freezing or going blank, settings resetting, and a "Transport Mode On" message after restart. Complaints mention dealers finding wiring or module issues, and some vehicles needed several restart attempts. Reported from very low mileage up to about 150,000 miles, with a spread across the model's life rather than one narrow window.

   1 related service bulletin

   What to check: Check that the cluster, infotainment, and warning chimes behave normally across several start cycles, and ask whether any module reprogramming or wiring repairs have been done.

   2 excerpts from owner complaints in NHTSA records

   “My vehicle idiot lights were flashing and the car felt as if it was going to stall on the road. Dealer said it was a faulty P6. Now when driving the car the entertainment unit locked up. Radio could not be changed, volume lowered. Pedals on steering column don't work. Even when car was shut off the radio still played and would cut off. Called my dealership. The earliest my Chevy dealer can look at it is next week.”

   NHTSA complaint #11490610, filed 2022-10

   “I was driving on express way 96W Left lane busy 5 o'clock traffic Car just died it was stop n go I could have been killed if it wasn't for a man that stopped behind me he couldn't help another person stopped and push the car in N To a grass area where at least I wouldn't be smashed in Called 911 state police inform help van He didn't look at it my friend was there to pick me up Called tow truck they dropped it off at Chevy dealership in Howell Mi”

   NHTSA complaint #11551752, filed 2023-10

Buying note. A pre-purchase scan for P0128 and a check of the cooling system, shifter, and transmission behavior on a test drive will tell you more than mileage alone. Ask for service records showing whether thermostat, radiator, or shifter repairs have already been done.

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.