Component Inspection

P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

Inspection/Repair - Component Inspection

Component Inspection

1. Check Thermostat
(1) Check cooling system coolant level and fill if low.
(2) Check for a proper cooling system operation. Especially check that cooling and condenser fan operates normally.
(3) Remove the thermostat and check the following items:
(1) Stuck or damaged
(2) Verify the temperature at which the valve is open : 80 - 84 °C (176 - 183.2 °F)
(4) Has a problem been found?
YES
1) Substitute with a known - good Thermostat and check for proper operation. If the problem is corrected, replace Thermostat and go to "Verification of Vehicle Repair" proprocedure.
NO
1) Go to "Verification of Vehicle Repair" procedure.