Engine Coolant Temperature

The engine computer is telling you that the engine coolant is too hot or too cold, which can lead to engine overheating or poor performance if not addressed.

The engine control module sees the coolant temperature reading and expects it to be within a specific range, typically between 180°F and 220°F when the engine is at operating temperature.

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; if it's low, top it up and retest. Decision: If the code returns, proceed to step 2; if not, issue resolved.
2. 22. Inspect the coolant temperature sensor wiring and connector for damage or corrosion. Decision: If damaged, repair or replace; if not, proceed to step 3.
3. 33. Check the operation of the coolant temperature sensor. Using a multimeter, verify that the sensor provides a resistance within the expected values as the temperature changes. Decision: If out of range, replace the sensor; if in range, proceed to step 4.
4. 44. Test the thermostat operation by running the engine and observing the coolant temperature. If it takes too long to reach normal operating temperature, replace the thermostat.

• Faulty coolant temperature sensor
• Coolant leaks leading to low coolant level
• Thermostat stuck open or closed
• Wiring issues between sensor and ECM

$$