Inspection Procedure 18: Overheating


COMMENTS ON TROUBLE SYMPTOM



  • The failure could possibly be caused by the failed engine cooling system, defective cooling fan system, faulty engine coolant temperature sensor and so on.

PROBABLE CAUSES



  • Insufficient amount or deteriorated quality of engine coolant
  • Failed cooling fan system
  • Failed engine coolant temperature sensor
  • Failed thermostat
  • Failed water pump
  • Failed radiator core
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is the diagnosis code set?
Inspection chart for diagnosis code (Refer to ).
Go to Step 2.

STEP 2. Check engine coolant.
note When the engine coolant level is too low, check for any section that cases leakage and repair, if necessary.

  • Check engine coolant (Refer to GROUP 14 - On-vehicle Service - Engine Coolant Leak Check ).

Q. Is the check result normal?
Go to Step 3.
Replace or fill the engine coolant.

STEP 3. M.U.T.-III actuator test

  • Item 14: Cooling fan motor
OK: Fan motor rotates at high speed.

Q. Is the check result normal?
Go to Step 4.
Check fan control relay system (Refer to GROUP 14 - Troubleshooting ).

STEP 4. M.U.T.-III data list

  • Item 6: Engine coolant temperature sensor
OK:
    Engine cold state: At ambient temperature (atmospheric temperature) or equivalent.
    Engine hot state: At 80 - 120°C

Q. Is the check result normal?
Go to Step 5.
Check engine coolant temperature sensor system. Check code No. P0117: engine coolant temperature sensor circuit low input (Refer to ). Check code No. P0118: engine coolant temperature sensor circuit high input (Refer to ).

STEP 5. Check thermostat.

  • Check thermostat (Refer to GROUP 14 - Thermostat - Inspection ).

Q. Is the check result normal?
Go to Step 6.
Replace the thermostat.

STEP 6. Check water pump.

  • Check water pump (Refer to GROUP 14 - On-vehicle Service - Water Pump Coolant Leak Check ).

Q. Is the check result normal?
Replace the radiator.
Replace the water pump.