2020 Cadillac XT6
Mileage
47,722
Service Date
7/16/2026
Services Performed
- Diagnostic Findings: Scanned vehicle and found DTC P0128 – Engine Coolant Temperature Below Thermostat Regulating Temperature stored in the ECM. Freeze-frame data indicates the engine did not reach the expected operating temperature within the required time after start-up. Performed cooling system inspection. Coolant level is acceptable and no external coolant leaks were found at this time. Monitored engine coolant temperature data with scan tool during warm-up. Engine coolant temperature rose slower than expected and remained below normal operating range, indicating the thermostat is not properly regulating coolant flow. Based on the fault code, scan data, and cooling system inspection, the thermostat appears to be stuck open or opening too early, preventing the engine from reaching proper operating temperature. Cause: Faulty thermostat / thermostat housing assembly causing engine coolant temperature to remain below the calibrated operating range. Correction Recommended: Replace thermostat assembly with required seals/gaskets. Refill and bleed cooling system as needed. Clear codes and perform road test to verify engine reaches proper operating temperature and that DTC P0128 does not return.
- THERMOSTAT HOUSING – Remove & Replace – 3.6L Eng w/Thermostat – [Includes: Drain and refill Cooling System. Includes: R&I Throttle Body Assembly. Includes: R&I Intake Manifold.]
Anthony M. gave our service a 5 star review on 7/16/2026
