Check the coolant level.

Is the coolant level below the add mark?

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Go to Step 2

Go to Step 3

1. Add coolant as necessary. Refer to Cooling System Draining and Filling .
2. Perform a cooling system pressure test. Refer to Cooling System Leak Testing .

Is the repair complete?

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System OK

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Check for a stuck open, missing, or wrong type of coolant thermostat. Refer to Thermostat Diagnosis .

Is the thermostat operating properly?

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System OK

Go to Step 4

Install the correct replacement thermostat. Refer to Engine Coolant Thermostat Replacement .

Is the repair complete?

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System OK

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