Engine Coolant Temperature Above Normal Operating Range

The computer sees that the coolant is too hot, which could lead to overheating and engine damage.

The ECM (Engine Control Module) is monitoring the engine coolant temperature sensor signal, looking for values typically between 185°F to 220°F (85°C to 105°C). When the temperature exceeds around 240°F (116°C), it triggers this fault 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 is at the recommended level. If low, top off and check for leaks after.
2. 22. Inspect for visible coolant leaks - Look for spots under the vehicle or damp areas around hoses, radiator, and engine block. Repair any leaks found.
3. 33. Test the coolant temperature sensor - With a multimeter, check the sensor's resistance versus temperature. Expect around 2.5 kΩ at 185°F (85°C). If readings are off, replace the sensor.
4. 44. Examine the thermostat operation - Remove the thermostat and test in boiling water; it should open by 203°F (95°C). If it doesn't, replace it.
5. 55. Check the water pump - Look for any signs of failure such as noise, leaks, or erratic coolant flow. Repair or replace if necessary.
6. 66. Inspect the radiator - Ensure there are no obstructions, and the fins are not clogged. Clean as needed. If damaged, replacement may be necessary.

• Low coolant level
• Coolant leak
• Faulty thermostat
• Failed water pump
• Blocked radiator
• Inaccurate coolant temperature sensor

$$$