The Lemon IndexThe engine isn't reaching normal temperature fast enough.
Drive on, get it checked. You can usually keep driving. Have the code read at your next service or within a few weeks.
Thermostat stuck open. Then: faulty coolant temp sensor; low coolant.
Owners named P0128 in 120 complaints to the U.S. government, most often on the Chevrolet Blazer.
Models that report it most
Complaints that name P0128, by model. Raw counts, not a failure rate: popular models get more complaints. Tap a model for its years, mileage and what owners say fixed it.
P0128 by model: P0128 Chevrolet Blazer (34) · P0128 GMC Acadia (23)
Years owners report it on most: 2020 Chevrolet Blazer · 2019 Chevrolet Blazer · 2019 GMC Acadia · 2020 GMC Acadia · 2016 Jeep Renegade · 2017 GMC Acadia
The details
What P0128 means
The engine isn't reaching normal temperature fast enough. The heater may blow cool and fuel economy drops.
Can I drive with P0128?
Drive on, get it checked. You can usually keep driving. Have the code read at your next service or within a few weeks.
18% of the owner complaints that name P0128 also say the car overheats. A complaint can describe more than one problem, so this doesn't prove the code caused it.
Common causes of P0128
- Thermostat stuck open
- Faulty coolant temp sensor
- Low coolant
A shop should confirm the cause with a scan and tests before replacing parts.
What owners describe
- Overheats: 18% of complaints
- Stalls or shuts off: 12% of complaints
- Warning lights and electrical faults: 12% of complaints
- Brakes or ABS act up: 8% of complaints
Share of complaints naming the code whose text also mentions each problem.
Model years that report P0128 most
2020 Chevrolet Blazer (15), 2019 Chevrolet Blazer (12), 2019 GMC Acadia (7), 2020 GMC Acadia (6), 2016 Jeep Renegade (4), 2017 GMC Acadia (4).
Related codes
P0126 P0123 P0122 P0121 P0120 P0131 P0133 P0135
Quick answers
What does P0128 mean?
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). The engine isn't reaching normal temperature fast enough. The heater may blow cool and fuel economy drops.
Can I drive with P0128?
Drive on, get it checked. You can usually keep driving. Have the code read at your next service or within a few weeks.
What causes P0128?
Thermostat stuck open; Faulty coolant temp sensor; Low coolant.
Counts: NHTSA owner complaints whose text names P0128. A complaint is an owner's report, not a diagnosis. Meanings: the standard SAE J2012 definitions in our own words; manufacturer codes only where verified for that make. General information, not repair advice for your car.