Engine Coolant Temperature Above Normal

The engine's computer checks how hot the engine coolant is and if it gets too hot, it triggers this code. This can happen if the coolant is low, the thermostat is stuck, or the cooling fan isn't working right.

The engine control module (ECM) reads the coolant temperature sensor input, typically around 194°F to 221°F (90°C to 105°C). If the reading exceeds the expected limits of around 230°F (110°C) or if the engine runs for a set time without cooling down, it sets the code.

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 topped off to the correct level. Decision: Is coolant low? Yes - Refill coolant and retest. No - Proceed to step 2.
2. 22. Inspect wiring and connectors to the coolant temperature sensor for damage or corrosion. Decision: Are any wiring issues found? Yes - Repair wiring/connectors and retest. No - Proceed to step 3.
3. 33. Measure the resistance of the coolant temperature sensor at different temperatures to ensure it's functioning properly. Decision: Is the sensor out of spec? Yes - Replace coolant temperature sensor and retest. No - Proceed to step 4.
4. 44. Check the operation of the cooling fan by monitoring it during engine operation. Decision: Does the fan operate correctly? Yes - Proceed to step 5. No - Repair or replace cooling fan and retest.
5. 55. Inspect the thermostat for proper operation. If stuck closed, replace the thermostat and retest.

• Low coolant level
• Faulty coolant temperature sensor
• Stuck thermostat
• Cooling fan not operating
• Blocked radiator
• Water pump failure

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