Engine Overtemperature
The engine is overheating beyond normal limits.
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)
The engine's temperature is rising too high, usually over 240°F (116°C), causing the ECM to trigger this code to avoid damage.
What the computer is actually seeing
The engine control module (ECM) monitors the coolant temperature sensor signal, which should return a voltage between 0.5V (cold) and 4.5V (hot). If it detects a temperature above the preset threshold for too long, it will log this fault.
What a healthy reading looks like
Coolant temperature should normally be between 180°F (82°C) and 220°F (104°C). A reading above 240°F (116°C) indicates overheating.
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 coolant level in the reservoir. Is it below the minimum line? If yes, top it off and see if the code returns.
- 22. Inspect for visible leaks in the hoses and radiator. Are there any signs of leaking coolant? If yes, repair and recheck the system.
- 33. Test the coolant temperature sensor using a multimeter. Is it outputting a voltage that correlates with the engine temperature? If no, replace the sensor.
- 44. Check the thermostat operation by feeling the upper radiator hose after engine reaches operating temperature. Is it hot? If no, replace the thermostat.
- 55. Verify that the water pump is functioning. Is there proper circulation of coolant in the system? If no, inspect/replace the water pump.
Common causes
- Low coolant level due to leaks
- Faulty coolant temperature sensor
- Engine oil issues like low oil level or poor lubrication
- Cooling system blockages
- Failed thermostat
- Water pump failure
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, driving while the engine is overheating can cause severe damage.
Will this code come back if I fix the coolant leak?
If all issues are resolved properly, the code should not return.
Why does it pair with SPN 110?
SPN 110 indicates the coolant temperature sensor is likely not reading correctly due to the engine overheating.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →