Engine Coolant Temperature Too High
The engine coolant temperature exceeds the predefined limit.
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What it means (plain English)
When the engine runs too hot, it can cause serious damage. The sensor is telling the computer that the coolant temperature is over 240°F (115°C).
What the computer is actually seeing
The engine control module (ECM) monitors the coolant temperature sensor input, which should normally fluctuate between 180°F (82°C) and 220°F (104°C) during normal operation. If the temperature reading exceeds set thresholds, the fault code triggers.
What a healthy reading looks like
Coolant temperature should be between 180°F (82°C) and 220°F (104°C) during normal running conditions.
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 overflow tank. Is it below the minimum mark? If yes, refill and reassess.
- 22. Inspect for visible leaks in the cooling system. If found, repair as needed and reassess the code.
- 33. Use a scan tool to monitor the coolant temperature sensor readings. Is it reading over 240°F (115°C) without obvious overheating? If yes, proceed to the next step.
- 44. Disconnect the coolant temperature sensor. Measure resistance at the sensor connector. Is it within specification (usually around 2000 Ohms at 70°F)? If no, replace the sensor. If yes, check the wiring for corrosion or breaks.
- 55. Check if the thermostat is opening properly. Remove the thermostat and test in hot water. Does it open fully at around 195°F (91°C)? If no, replace the thermostat.
Common causes
- Low coolant level
- Faulty coolant temperature sensor
- Coolant leaks
- Thermostat stuck closed
- Radiator blockage
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, driving with an overheating engine can cause severe damage to the engine.
Will this code come back after I clear it?
If the underlying issue isn't fixed, the code will likely return after clearing.
Why does this code sometimes pair with SPN 460?
SPN 460 indicates excessive coolant temperature. Both codes can trigger if the overheating issue is severe.
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