2020 GMC Canyon
Mileage
74,628
Service Date
11/22/2025
Services Performed
- Connected a scan tool and found code P0128 – Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). With the scan tool connected to monitor live data, found that the engine coolant temperature parameter was below the specified 195 to 212 degrees Fahrenheit normal operating temperature. Used a non-contact pyrometer to verify the actual temperature at the engine coolant thermostat housing inlet and outlet and found that the temperature was equal but below the normal operating temperature. Performed a road test and found that the engine temperature never reached the normal operating temperature according to the scan tool. Found that the thermostat was stuck open. The engine thermostat is integrated into the thermostat housing and is replaced as an entire unit. These test results verified that the engine coolant thermostat and thermostat housing were faulty.
- DRAIN COOLING SYSTEM COMPLETELY. REMOVE ALL NECESSARY COMPONENTS TO GAIN PROPER ACCESS TO THE THERMOSTAT ASSEMBLY, INCLUDING ANY HOSES, COVERS, OR BRACKETS OBSTRUCTING THE AREA. REMOVE AND REPLACE THE THERMOSTAT HOUSING, THE THERMOSTAT ITSELF, AND THE INCLUDED GASKET TO ENSURE A PROPER SEAL AND CORRECT OPERATION. REASSEMBLE ALL COMPONENTS, MAKING ANY NECESSARY ADJUSTMENTS TO ENSURE CORRECT FITMENT. REFILL THE SYSTEM WITH FRESH ANTI-FREEZE COOLANT, BLEED ANY AIR FROM THE SYSTEM, AND THOROUGHLY TEST ALL AFFECTED AREAS TO VERIFY PROPER ENGINE TEMPERATURE REGULATION AND LEAK-FREE OPERATION.
STEVE A. gave our service a 5 star review on 12/4/2025
