Engine System Over Temp

The engine is running hotter than usual, which can lead to overheating and serious damage.

The engine control module (ECM) is monitoring temperature from the engine coolant temperature sensor. When the temperature exceeds a preset threshold, typically around 240°F (115°C), this code is triggered.

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 coolant level in the reservoir. Ensure it's at the proper level. If low, fill and see if issue persists. Decision: If coolant is low, refilling may fix the issue. If not, proceed to step 2.
2. 22. Inspect for leaks around hoses and connections. Look for signs of coolant on the ground or visible wetness. Decision: If leaks are found, repair them and check if the code returns. If no leaks are found, proceed to step 3.
3. 33. Test the engine coolant temperature sensor using a multimeter. It should read a resistance value relative to the temperature (for instance, about 200 ohms at 200°F). Compare to expected values. Decision: If sensor is faulty, replace it. If it tests okay, proceed to step 4.
4. 44. Check the thermostat operation by monitoring engine temperature during warm-up. If it exceeds 220°F without opening, it may be stuck closed. Decision: If thermostat is faulty, replace it. If it's functioning, proceed to step 5.
5. 55. Examine coolant flow. Inspect for collapsed hoses or blockages in the cooling system. You want to ensure coolant is circulating properly. Decision: If flow is obstructed, fix any mechanical issues. If flow is good and code persists, further investigation may be necessary.

• Low coolant level
• Faulty engine coolant temperature sensor
• Coolant leaks
• Collapsed hoses or blockages
• Thermostat stuck closed

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