Engine Coolant Temperature High
The engine control module has detected that the engine coolant temperature exceeds normal operating range.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
Your engine coolant is too hot, which can happen if the cooling system is not working properly or if the engine is heavily loaded.
What the computer is actually seeing
The ECM reads the coolant temperature sensor input, which should be around 190°F to 220°F during normal operation. If it reads higher than 240°F or if the signal indicates an unrealistic temperature, this will trigger the fault code.
What a healthy reading looks like
Engine coolant temperature should be between 190°F and 220°F when the engine is running normally; above 240°F triggers this code.
Guided diagnostic — the DiagCoach way
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.
- 11. Check the coolant level in the reservoir, add if low. Decision: If coolant is low, refill and retest.
- 22. Inspect for visible coolant leaks in hoses, radiator, and engine block. Decision: If leaks are found, repair and retest.
- 33. Test the engine coolant temperature sensor using a multimeter. Expected resistance at 77°F (25°C) is around 2,500 ohms. Decision: If out of spec, replace the sensor and retest.
- 44. Check the operation of the thermostat by monitoring engine temperature as it warms up. Decision: If the engine does not reach 195°F after 10-15 minutes of running, replace the thermostat and retest.
- 55. Verify that the cooling fan engages when the coolant temperature reaches 220°F. Decision: If the fan does not engage, troubleshoot fan circuit (relay, wiring) and replace if necessary.
Common causes
- Coolant leaks leading to low coolant level
- Faulty thermostat stuck closed
- Failed engine coolant temperature sensor
- Cooling fan not operating
- Blocked radiator or cooling system
- Water pump failure
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It can lead to engine overheating, so avoid driving until the issue is resolved.
Will this code come back after clearing?
If the underlying issue is not fixed, the code likely will return.
Why does it pair with other SPNs?
Cooling issues can affect multiple systems, leading to more fault codes.
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