2019 Chevrolet Blazer: check engine light

Filed Nov 2, 2026 · Engine, Steering · VA

Steering assist reduced message appeared Check engine light appeared, po128 code, thermostat and sensor defect. Common problem with these vehicles, GM has only recalled 2021 model even though the same engine and thermostat are on all V-6 models. Contacted GM, no assistance available on my year Blazer.

Filed Aug 18, 2026 · Engine, Transmission · NY

Thermostat went bad at 47,500 miles. Temp gauge stopped working, Engine light came on and alert stating steering assist is reduced

Filed Feb 24, 2026 · Engine · IL

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.

Filed Dec 18, 2025 · Driver assistance · KY

I have replaced the thermostat sensor 3 times because keep getting assist driver assistance disabled throws code p1028 code coolant drops check engine light come on the auto stop quits working

Filed Oct 28, 2025 · OH

The thermostat is stuck open and needs replaced. If left as it is, could create overheating issues for the engine and even more damage. A service engine light was illuminated prior to finding the issue. The light was accompanied by a warning about assisted steering. Two days after the light first came on, a Chevrolet service department diagnosed the problem and is repairing it. An invoice can be provided at a later date once repairs are completed.

Filed Oct 1, 2025 · Electrical, Engine · AZ

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.

Filed Jun 15, 2025 · Electrical, Engine · OH

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.

Filed Jun 9, 2025 · Electrical · GA

coolant temp gauge stuck on cold, AC quits blowing cold air, reads the thermostat code when check engine light comes on. Was told my car needs a new thermostat and a coolant temp sensor. This has proven to be a common issue among Blazers. there is no rhyme or reason when this happens and will fix itself after a while, but then happens again.

Filed May 20, 2025 · CA

My check engine light is on the, the temperature meter is stuck on cold, the A/C only blows hot air, and the engine fan is blaring loud as heck the moment the car is started. Also it keeps telling me the steering assist has failed. I have replaced the battery and checked the coolant. Still the same issues.

Filed Apr 28, 2025 · NH

My check engine light came on (solid) and my AC stopped blowing cold air and my auto start stopped working. I used a diagnostic tool to read the code and it said "P0128 Coolant Thermostat $07e8". The same thing happens with my heat when it gets too cold out.

Filed Apr 25, 2025 · Acceleration, Engine · UT

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.

Filed Apr 22, 2025 · MS

Action Required: Steering Assist is Reduced Drive with Care & Check Engine Light comes on after the alert message. When these are on, the ac does not get cold. Unhooking the battery resets it for a few days and then it comes back on.