High Engine Coolant Temperature
Engine coolant temperature is above normal operating range.
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What it means (plain English)
The engine computer thinks your engine is too hot, over 230°F (110°C), which can cause damage if not corrected.
What the computer is actually seeing
The ECM (Engine Control Module) reads the coolant temperature sensor signal. When the temperature exceeds the set threshold (typically 230°F), it triggers the SPN 14 fault code.
What a healthy reading looks like
Coolant temperature should normally be around 190-220°F (88-104°C).
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 – add coolant if low. Decision: Is the level correct? Yes: Go to next step; No: Top up coolant and retest.
- 22. Inspect the coolant temperature sensor connection for corrosion or damage – clean or repair as necessary. Decision: Is the connector good? Yes: Go to next step; No: Repair connector and retest.
- 33. Test the coolant temperature sensor using a multimeter, looking for a resistance value of approximately 2.5 kΩ at 77°F (25°C) and check the signal wire voltage at the ECM. Decision: Is the sensor reading correctly? Yes: Go to next step; No: Replace the coolant temperature sensor.
- 44. Check engine operation and thermostat function – if the engine is overheating still, replace thermostat. Decision: Is the engine running at normal temperature? Yes: Consider other cooling system issues; No: Replace thermostat and retest.
Common causes
- Failed coolant temperature sensor
- Engine overheating due to low coolant level or leaks
- Faulty thermostat stuck closed
- Cooling fan not working properly due to electrical issues
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, it's not safe as the engine could overheat and cause serious damage.
Will this code come back after repairs?
If the root cause is fixed, this code should not reappear.
Why does this code often pair with other SPN codes?
Overheating can affect multiple systems, causing related fault codes to trigger.
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