For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 |

1. Allow the engine to cool.
2. START the engine.
3. Monitor the engine coolant temperature using the tech 1 .
4. Check the radiator inlet hose temperature by feeling the hose while monitoring the engine coolant temperature.

Is the radiator inlet hose cool to the touch until the coolant temperature reaches at least 83°C (181°F)?

--

Go to step 3

Go to Step 2

2 |

1. Install a new engine coolant thermostat. Refer to Engine Coolant Thermostat Replacement .
2. Recheck the cooling system, using the tech 1 , to be sure the system is OK.

Is there still slow warm up, or not enough heat?

--

Go to step 3

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3 | The problem is caused from something other than a faulty thermostat. Refer to Engine Fails To Reach Normal Operating Temperature . Is the repair complete? | -- | System OK | --