Engine Coolant Temperature - High

The engine is running too hot, which can lead to overheating and damage if not addressed quickly.

The engine control module (ECM) detects coolant temperature above 221°F (105°C) and sets a fault code to prevent severe engine damage.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 11. Check the coolant level in the reservoir and radiator. Ensure it's at the proper level. Decision: If low, add coolant and re-check. If okay, proceed to step 2.
2. 22. Inspect the coolant temperature sensor wiring and connector for damage or corrosion. Decision: If damaged, repair or replace the wiring/connector; if okay, proceed to step 3.
3. 33. Use a scan tool to check the current reading of the coolant temperature sensor. It should read within the normal range. Decision: If the reading is low with hot engine, replace the coolant temperature sensor; if it's high, proceed to step 4.
4. 44. Check the thermostat operation by feeling the upper radiator hose; it should get hot as the engine warms up. Decision: If it stays cold for too long, replace the thermostat; if it gets hot, check the radiator for blockages.
5. 55. Inspect the water pump for any signs of failure or leaks. Decision: If it's not circulating properly, replace the water pump.

• Low coolant level
• Failed coolant temperature sensor
• Thermostat stuck closed
• Blocked or damaged radiator
• Water pump failure

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