What does code P0128 mean and is it safe to drive?
P0128: Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature). Here’s what it means, what usually causes it, what repairs typically cost, and how urgent it is to keep driving.
PowertrainGenerally safe to drive
Repair cost
$100–$350
System
Powertrain
Urgency
low
What this code means
The engine is not reaching normal operating temperature in the expected time. Usually a stuck-open thermostat.
Common causes
- Thermostat stuck open
- Coolant temperature sensor fault
- Low coolant level
Symptoms
- Check Engine Light
- Heater may blow cold
- Poor fuel economy
- Temperature gauge stays low
Typical fixes
- Replace thermostat
- Replace coolant temperature sensor if faulty
- Refill coolant and check for leaks
Repair cost range
Repairs for P0128 often fall between $100 and $350, depending on the cause and your vehicle.