Diagnosis and check 4.4L (Discovery 3)

Inspection and verification

1. Make sure the customer's complaint is valid.

2. Visually inspect for obvious mechanical and electrical problems.

Mechanical factors	Electrical Factors
Coolant leaks coolant hoses Coolant expansion tank Radiator heater radiator Accessory drive belt Viscous fan	Fuses Wiring harness Loose or corroded connector (ov) coolant temperature sensor (ECT)

3. If an obvious cause of the problem you identified or described by the client is found, eliminate it before proceeding to the next steps (if possible).

4. Use an approved diagnostic system or scan tool (tester), to retrieve all DTCs before referring to the symptom table or DTC index (DTC).

Clear all DTCs after troubleshooting.

Symptom table

Symptom	Possible reason	Actions
Loss of coolant	Hoses Hose connections Radiator coolant pump heater radiator Gaskets Cracks in engine castings Cylinder block rod plugs	Perform a visual inspection. If there are no obvious leaks, perform a pressure test using the service station equipment. Repair if necessary. Refer to the relevant section in the workshop manual.
Overheat	Low/contaminated coolant Thermostat Viscous fan ECT sensor Obstacles in the passage of air flow through the radiator	Check the level and condition of the coolant. Check the thermostat and make any necessary repairs. Perform a pressure test on the cooling system. Check the operation of the viscous fan, make sure the viscous fan rotates freely. Check for airflow obstructions through the heatsink. Repair if necessary. Refer to the relevant section in the workshop manual.
Engine does not reach normal temperature	Thermostat Viscous fan	Check thermostat operation. Check the operation of the viscous fan, make sure that the viscous fan does not stick.

DTC index

DTCs	Description	Possible reasons	Actions
P011623	Engine Coolant Temperature Sensor 1 Circuit Range/Performance Problems	Low coolant level Engine thermostat malfunction ECT Sensor Signal Circuit Intermittent High Resistance ECT sensor malfunction	Check coolant level and thermostat operation (stuck open). Refer to the relevant section in the workshop manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
P011624	Engine Coolant Temperature Sensor 1 Circuit Range/Performance Problems	Low coolant level Engine coolant thermostat malfunction ECT Sensor Signal Circuit Intermittent High Resistance ECT sensor malfunction	Check coolant level and thermostat operation (stuck open). Refer to the relevant section in the workshop manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
P011629	Engine Coolant Temperature Sensor 1 Circuit Range/Performance Problems	Low coolant level Engine coolant thermostat malfunction ECT Sensor Signal Circuit Intermittent High Resistance ECT sensor malfunction	Check coolant level and thermostat operation (stuck open). Refer to the relevant section in the workshop manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
P011700	Engine Coolant Temperature Sensor 1 Circuit Low Voltage (ECT)	ECT sensor disconnected ECT sensor signal circuit high resistance, short to voltage ECT sensor malfunction	Refer to the guided diagnostic program for this code on the approved diagnostic system.
P011800	High voltage in the electrical circuit of the engine coolant temperature sensor 1 (ECT)	Engine Overheating Condition/Cooling Fan Malfunction ECT sensor wiring short to ground ECT sensor malfunction	Check coolant level and thermostat operation (sticking in the closed position). Check for cooling fan DTCs. Refer to the guided diagnostic program for this code on the approved diagnostic system.