:  Dec 17, 2007



Inspection and verification

. Verify the customer concern.

. Visually inspect for obvious mechanical or electrical faults.

Mechanical Electrical
  • Coolant leaks
  • Coolant Hoses
  • Coolant expansion tank
  • Radiator
  • Heater core
  • Accessory drive belt
  • Viscous fan
  • Fuses
  • Wiring harness
  • Loose or corroded connector(s)
  • Engine coolant temperature (ECT) sensor

. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

. Use the approved diagnostic system or a scan tool to retrieve any diagnostic trouble codes (DTCs) before moving onto the symptom chart or DTC index.
  Make sure that all DTCs are cleared following rectification
Make sure that all DTCs are cleared following rectification

Symptom chart

Symptom Possible cause Action
Coolant loss
  • Hoses
  • Hose connections
  • Radiator
  • Water pump
  • Heater core
  • Gaskets
  • Engine casting cracks
  • Engine block core plugs
Carry out a visual inspection. If there are no obvious leaks, carry out a pressure test using your workshop tester. Rectify as necessary. Refer ti the relevant section of the workshop manual.
Overheating
  • Low/Contaminated coolant
  • Thermostat
  • Viscous fan
  • ECT sensor
  • Restricted air flow over the radiator
Check the coolant level and condition. Check the thermostat and rectify as necessary. Carry out a cooling system pressure test. Check the viscous fan operation, make sure the viscous fan rotates freely. Check for obstructions to the air flow over the radiator. Rectify as necessary. Refer to the relevant section of the workshop manual.
Engine not reaching normal temperature
  • Thermostat
  • Viscous fan
Check the thermostat operation. Check the viscous fan operation, make sure the viscous fan is not seized.

DTC index

DTC Description Possible causes Action
P011623 Engine Coolant Temperature Sensor 1 Circuit Range/Performance
  • Low coolant level
  • Engine thermostat failure
  • ECT sensor sensing circuit intermittent high resistance
  • ECT sensor failure
Check the coolant level and the thermostat operation (stuck open). Refer to the relevant section of the workshop manual. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
P011624 Engine Coolant Temperature Sensor 1 Circuit Range/Performance
  • Low coolant level
  • Engine coolant thermostat failure
  • ECT sensor sensing circuit intermittent high resistance
  • ECT sensor failure
Check the coolant level and the thermostat operation (stuck open). Refer to the relevant section of the workshop manual. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
P011629 Engine Coolant Temperature Sensor 1 Circuit Range/Performance
  • Low coolant level
  • Engine coolant thermostat failure
  • ECT sensor sensing circuit intermittent high resistance
  • ECT sensor failure
Check the coolant level and the thermostat operation (stuck open). Refer to the relevant section of the workshop manual. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
P011700 Engine Coolant Temperature Sensor 1 Circuit Low
  • ECT sensor disconnected
  • Engine coolant temperature (ECT) sensor sensing circuit high resistance, short circuit to power
  • ECT sensor failure
Refer to the guided diagnostic routine for this code on the approved diagnostic system.
P011800 Engine Coolant Temperature Sensor 1 Circuit High
  • Engine overheat condition/cooling fan failure
  • ECT sensor wiring short circuit to ground
  • ECT sensor failure
Check the coolant level and the thermostat operation (stuck closed). Check for cooling fan DTCs. Refer to the guided diagnostic routine for this code on the approved diagnostic system.