1. Ensure that the cooling system is full.
2. Allow the engine to cool.
3. Start the engine.
4. Turn the air conditioning system off.
5. Inspect the engine cooling fan(s).

Is the electric cooling fan on?

Go to Step 2

Go to Step 3

1. Diagnose and repair the cooling fan system. Refer to Cooling Fan Always On.
2. Verify the customer complaint.

Does the engine still fail to reach normal operating temperature?

Go to Step 3

System OK

Install the Scan Tool to the DLC. Compare the Scan Tool coolant temperature reading to the I/P cluster coolant temperature.

Is the I/P cluster coolant temperature close to the reading on the Scan Tool?

Go to Step 5

Go to Step 4

1. Diagnose and repair the coolant temperature gauge system.
2. Verify the customer complaint.

Does the engine still fail to reach normal operating temperature?

Go to Step 5

System OK

Inspect the thermostat for correct operation. Refer to Thermostat Diagnosis.

Is the thermostat operating correctly?

System OK

Go to Step 6

1. Replace the thermostat. Refer to Engine Coolant Thermostat Replacement.
2. Verify the customer complaint.

Does the engine still fail to reach normal operating temperature?

Go to Step 1

System OK