P0128 on Chevrolet vehicles
44 owner complaints filed with NHTSA about Chevrolet vehicles mention P0128 (Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)) - across 8 models. Below is where it shows up, by model and year.
Can you drive with it? Yes, safely. Fuel economy and heater performance suffer until fixed - and in most states it fails emissions readiness.
Symptoms, likely causes in order and realistic repair costs are on the main P0128 page - they do not differ much by brand. This page shows what is specific to Chevrolet: which models and years actually report it.
Chevrolet models reporting P0128
The number next to each year is how many NHTSA complaints for that car mention P0128. Owners rarely quote trouble codes when complaining, so real occurrence is many times higher - use these numbers to compare years, not as totals.
What Chevrolet owners report
“The contact owns a 2023 Chevrolet Blazer. The contact stated that while driving, a code appeared on the dashboard P0128. When the vehicle's engine was switched off, the engine cooling fan continued to run. Warning light stating the steering would be disable.; however power steering was not lost. The vehicle was taken to a dealer where it was diagnosed with a thermostat failure. The manufacturer was notified of the failure. The approximate failure mileage was 48,000”2023 Chevrolet Blazer · May 2026
“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.”2020 Chevrolet Blazer · May 2026
“Thermostat stuck open radiator broke. Told by 4 GM Dealerships, this is a very common problem in a GM 3.6L V6. GM even claims it's common in its Tech Advisements. The "Stuck Open" Glitch (P0128 Code)”2020 Chevrolet Blazer · May 2026
“I have a 2022 Blazer with a 3.6 engine. The thermostat has failed and dealer says only certain blazer vehicles are covered under aspecial warrnty exstesion. I know several people having the same problem.I have a check engine light, with a scan shows code P0128(thermostat0. I also have a display of power steering assist reduced and tempature gauge stays much lower than normal.. When you turn vehicle off the high speed cooling fans remain running ub=ntil battery is dead.”2022 Chevrolet Blazer · Apr 2026
Counts are NHTSA owner complaints whose text mentions P0128 - owner-reported and unverified. Always confirm with a diagnosis of your specific vehicle.