What does code P0128 mean on a Buick and is it safe to drive?
P0128: Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature). Here's what it means on your Buick, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
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What this code means
The engine is not reaching normal operating temperature in the expected time. Usually a stuck-open thermostat.
Common causes for your Buick
- 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
For a Buick, repairs for P0128 often fall between $100 and $350, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Buick
Buick P0128 on the 3.6L LFX and 2.4L Ecotec mirrors the same thermostat housing issues seen in Chevrolet. The map-controlled thermostat and plastic housing on the Ecotec 2.4L can fail as a unit.
Most commonly affected models
LaCrosse 2010–2016Enclave 2008–2017Verano 2012–2017