2010 Cadillac P0128: What It Means & Is It Safe to Drive?
P0128 on the 2010 Cadillac: Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe 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 on the 2010 Cadillac
- 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 2010 Cadillac, repairs for P0128 typically fall between $100 and $350, depending on the root cause and labor rates in your area.
Known issues on Cadillac
Cadillac P0128 on the 3.6L LFX (ATS, CTS, SRX) and 2.0T engines follows GM's thermostat housing failure pattern. The plastic housing cracks with age—replace the housing assembly rather than just the thermostat element.
Most commonly affected models
CTS 2008–2015SRX 2010–2016ATS 2013–2018