2019 Chevrolet Blazer Engine Problems

Electronically controlled thermostat and sensor fail or get stuck at a much lower coolant temperature causing the dash to display the “steering assist is reduced drive with care.” It isn’t just a message, the steering is much harder to use potentially causing an accident. The ac completely doesn’t work causing potential for sensitive, elderly, or young children and pets to overheat inside, it’s significant risk of injury or death from the hot summer temperatures. The engine coolant temperature gauge is all the way down on C position which isn’t registering how hot/cold the engine gets potentially causing damage to the vehicle and a total loss of the vehicle entirely due to damage from the engine overheating. GM sent out letters to 2021 blazer owners which included a special coverage number N252508350 applying to people with this year having this problem and they have until 2036 or 150,009 mi to get the repairs made free of charge, they just bring the document with the special repair codes to the dealer and they fix it free of charge. After doing research online, this problem is affecting all years of the 2019+ blazers with the 3.6L V6 engine AND other known problems with other models and years of their other lineup of cars, it’s very widespread across their platforms. So what are people supposed to do when it isn’t the 2021 year? Pay an $800+ repair bill to GM when they KNOW it’s more widespread than just this year/make? This is a scam. I can’t even do the repair myself because I’m having trouble finding the correct parts online and not only that the repair is extensive, the whole top half of the engine needs to be taken apart just to get to the thermostat, we’re talking the airbox and intake manifold, all the plastic parts and shrouds and sensors covering engine, the fuel rail and injectors, pipes and clamps, engine coolant needs drained and refilled. It’s a major fix. I’m reporting this complaint to raise awareness and hopefully GM will do the right thing.

NHTSA ID

11739939

Incident

Mar 3, 2026

The vehicle will not shut off when you shift to park. You are forced to sit in the vehicle for extended periods of time attempting to get the vehicle turned off. Apparently Chevy is familiar with eat problem and there are pending class action law suits in Ohio. According to the dealership Chevy has acknowledged there is a defect but no recall has been issued. We have had this issue for about two months and it is getting worse.

NHTSA ID

11730819

Incident

Mar 30, 2026

Faulty thermostat. Check engine light comes on due to thermostat getting stuck open and needing to be replaced. This is terrible for the engine and the environment.

NHTSA ID

11720293

Incident

Feb 24, 2026

Thermostat Housing Replacement + Dexcool: P0128, thermostat stuck. Was told this can cause engine to overheat.

NHTSA ID

11716857

Incident

Feb 9, 2026

The thermostat has been sticking, and needs to be replaced after only 30,000 miles.

NHTSA ID

11715177

Incident

Sep 1, 2025

Was getting a steering assist reduced error code. Auto stop quit functioning and air conditioning stopped cooling. Engine sounded like a jet. P 0128 thermostat error code came up and had to be replaced. I see lots of similar complaints. Cost me $700.

NHTSA ID

11711579

Incident

Aug 1, 2025

We are noticing the coolant meter seems to be stuck on C, the AC is not blowing cold and we are getting a message that ACTION REQUIRED steering assist is reduced, drive with CAUTION. Today the brakes slammed on by themselves and almost sent my wife thru the windshield. Luckily she was in a clear area with no other cars around.

NHTSA ID

11699307

Incident

Nov 12, 2025

Engine temperature gauge is not working. Dash is displaying driver assist issue and steering intermittently locks up while moving. Air conditioning does not work and cooling fan is running at high speed. Thermostat and coolant temperature sensor need to be replaced. Such a high number of these vehicles are failing that i can’t even get factory parts

NHTSA ID

11694417

Incident

Oct 19, 2025

Dashboard goes on like a Christmas tree (almost all lights turn on ABS GAS LIGHT TRACTION CONTROL PARKING SERVICE LIGHT) check engine stays on then disappears after a few days. Transmission won’t gear into shifts only stays in one shift.

NHTSA ID

11690844

Incident

Oct 1, 2025

Thermostat has gone bad. Talked to Chevy and they said it is a known issue.

NHTSA ID

11685800

Incident

Sep 6, 2025

I keep getting this message that pops up, "Steering Assist reduced Drive with Care". At the same time this happens the temp gauge stays on cold, the ac quits working, the engine fan is on high, and most of the time I get code PO128. We have had it in to the dealer and they said the its the thermostat or the temp sensor. From what I am reading it could be a factory issue with the EMI issue from sensitive ECT circuitry. This has been an ongoing issue for us for over a year.

NHTSA ID

11683213

Incident

Aug 1, 2024

Diagnosed as a bad thermostat. AC not working. Steering assist issue. Temp gage not working. Car is out of warranty.

NHTSA ID

11668473

Incident

Jun 22, 2025

At startup, I would receive a message that said, steering assist reduced. There were no check engine lights or warning lights. My air conditioning stopped working, and my temperature gauge on the dash remained at cold. I also noticed the radiator fans were on full blast, continuously. I called the dealer, and they weren't sure what was causing that. I told them I was getting codes #U0401 & P0128. They asked me to clear the codes to see if they returned. I cleared the codes, but they returned immediately on restart of the engine. I'm going to replace the thermostat but i didn't understand the #U0401 code, so did further research. I found 2017 Bulletin #17-NA-158 which seamed relevent to my issues, and Vehicle Fitment that confirmed my 2019 Chevy Blazer is included. I then came to find that the un-shielded low voltage wires for the coolant temperature sensor are routed through the same harness as high voltage coil wiring. Some of us know that EMI will affect low voltage signals. As an HVAC system designer, I know that un-shielded low voltage communication wiring cannot run parallel two line voltage power wiring. The effects are not continuous, but definitely reoccurring. I also understand there has not been a recall for this issue which surprises me. I can replace the thermostat even in its difficult position, but I don't feel comfortable in separating the low voltage wiring from the harness. I understand that dealers who are aware of this issue, charge a hefty fee to do so. It's definitely one that I can't afford.

NHTSA ID

11666997

Incident

Jun 11, 2025

Temp gauge intermittently reads cold, no ac and engine cooling fan constantly blowing, dash warning re power steering, 40,000 miles, code po128, review of google indicates this is a common problem and likely needs a new thermostat and ect

NHTSA ID

11664173

Incident

May 21, 2025

35,000 miles and P0128 code that does not resolve after expensive repairs of coolant Temperature sensor and thermostat multiple times.

NHTSA ID

11661668

Incident

May 17, 2025

P0128 error, power steering reduced warning, cooling fans on, no a/c and temp gauge stuck on cold

NHTSA ID

11659823

Incident

May 8, 2025

"shift to park" message appears when parked (even if safety brake is engaged) and attempting to turn off the vehicle. The vehicle does not turn off and remains running for various periods of time. Unable to turn the vehicle off, leaving it unsecure and drains the battery. This happens consistently. I contacted my local dealership and they confirmed getting several of these reports through their shop, but no recall has been made.

NHTSA ID

11659193

Incident

May 6, 2025

The Blazer is having a recurring P0128 code. We have informed the dealership. This has been going on for 2 years or so. I reset the code with a code reader and it stays off for a few months usually. Tried to have the dealership look at it one of the last times it happened but they wouldn't just look at it...they wanted to set up an appointment. We needed the car so I reset the code again. Now it is time to get it fixed. I know it needs a thermostat and temperature sensor. The cost to install it will be close to $1000. This should not be at my cost. This is a know issue with the 3.6L engine and it affects the emissions of the vehicle along with many other parts of the engine. I am reaching out to see what can be done.

NHTSA ID

11657094

Incident

Dec 2, 2024

engine - code p0128 engine coolant thermostat. This is a safety issue because it reduces the power steering on vehicle, auto stop stopped working, unable to remote start vehicle. Issue has been confirmed at an independent service center (I work at an auto collision center). Warning lamp - check engine light. Message on dash - power steering reduced. Appears everything came on at the same time. Per dealership items most likely needing replacement are engine coolant thermostat and engine coolant temperature sensor but ecm module could also need replacement. Advised common problem but no recall power train - transmission shutters when accelerating. Safety is at risk because vehicle will not accelerate or accelerate too quickly. Called to dealership advise flush transmission fluid twice to fix issue. We have done this 4 times in the past year. Shutter temporarily reduces but does not go away. Per service advisor it is a "function design" and if flushing transmission fluid does not fix issue then transmission will need to be replaced. There are no warning lights or messages on dash electrical - vehicle says shift to park when vehicle is in park and will not allow vehicle to turn off. It is a safety issue because vehicle will not shut off. Problem confirmed by an independent service center we have already replaced the in-line wire harness jumper. This did not fix the issue. Advised from service center that entire shifter would need to be replaced.

NHTSA ID

11656851

Incident

Apr 1, 2025

Coolant Thermostat needs replaced at 59945 miles. The temperature gauge stopped working and the A/C unit shut off. The temperature outside created a safety issue for my family and I to ride in the car. The engine light came on and a message that stated the Steering Assist was effected. This should not happen in a car under 60000 miles.

NHTSA ID

11655329

Incident

Apr 15, 2025

Po128 temp. Below normal, happens on a regular basis, at least 2 times a week,

NHTSA ID

11655087

Incident

Jul 20, 2024

1. Wire harness with coil wires is the problem. It was fixed by a local shop and the vehicle can be inspected if needed. 2. The car throws a code for a faulty thermostat/coolant temp sensor. This will not allow the car get to oporating temp and could cause engine damage or not perform properly causing risk of an accident. Also this will reduce the driver assist features such as lane assist and adaptive cruise/braking. 3. Yes. 4. A local shop inspected the thermostat and coolant temp sensor and they oporated as they should. 5. The engine light comes on for the reasons mentioned above. It also has a "driver assist reduced" message. It appeared randomly while driving and stayed on for multiple days. Vehicle had a code for a bad thermostat/coolant temp sensor and "driver assist reduced" message. The cause is NOT the temp sensor or thermostat and is actually a wiring harness that two wires need to be separated from the bunch. The frequency from one wire interferes with the coolant temp sensor wires. I am on several forums for chevy blazers and there are TONS of posts about this issue with the 3.6 V6. Most people will go in and have these expensice parts replaced. It is not acceptable to have people get charged for a $800+ job when the part is not faulty.

NHTSA ID

11654938

Incident

Nov 16, 2024

Reduced steering warning, the temperature gague is stuck on C, radiator fan is running on high as soon as I start my car and the transmission is shifting hard at second and third gears.

NHTSA ID

11647213

Incident

Mar 8, 2025

My 2019 Blazer gave a Steering Assist warning on 2 Nov 2024. I was aware of a recall for other Blazers but for some reason my VIN was not among those recalled. I took it to the dealership on 6 Nov 2024. The dealership has determined that the issue is indeed the same issue with those other Blazers that have been recalled but refuses to include my car in the recall because the VIN number wasn't originally among that recall. I was told that the car needed anew temperature gage and that they would have to order it, however, the component was available outside of the dealership. I paid for the diagnostics and the part, being told that the light(s) would stay on, I would still be able to drive it and that I would receive a call when the part came in. It is my understanding that the steering assist reduced can affect the power steering and essentially revert back to manual power steering, potentially causing a loss of control while driving and increasing the risk of accidents. There were no warnings of the steering failure assist warning. It just appeared on Nov 2, 2024 at 1130am. About 1240pm I noticed that the temp gage was inop and the check engine light was now illuminated. I contend that because GM has already identified the thermostat issue serious enough to do a recall, then all Blazers with that recall issue, VIN number aside, should be given the same consideration and not have to pay for something that GM has already taken responsibility for. The dealership however does not agree for the simple fact that the VIN was not identified in the original recall.

NHTSA ID

11623882

Incident

Nov 2, 2024

We had the shift to park issue 3 years ago and fixed it. Cost near $300. Now we are taking it back in for the same exact issue. In addition to this issue all the lights on the dash board keep coming sporadically and on star sent us report with a ton of engine and transmission issues.

NHTSA ID

11607869

Incident

Mar 1, 2021