P0128

DTC P0128: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

Wiring Diagram

Wiring Diagram:

DTC Detecting Condition and Trouble Area

DTC Detecting Condition And Trouble Area:

DTC Confirmation Procedure

NOTE: Check to make sure that the following conditions are satisfied when using this "DTC Confirmation Procedure".
- Intake air temperature: 70 °C (158 °F) or higher.
- Engine coolant temperature at engine start: between -10 °C (14 °F) and 56 °C (133 °F).
- The following to DTCs are not detected: MAF sensor, IAT sensor and ECT sensor (other than P0128).

1 With ignition switch OFF, connect scan tool.
2. Turn ON ignition switch, clear DTC if any.
3. Start engine and run it for 20 minutes.
4. Check DTC and pending DTC by using scan tool.

DTC Troubleshooting
Refer to DTC P0116: Engine Coolant Temperature Circuit Range / Performance.