Engine Coolant Temperature
Indicates the engine coolant temperature is out of range.
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What it means (plain English)
The computer monitors the engine coolant temperature through a sensor. If the coolant gets too hot, it can cause engine damage. The system sees high or low coolant levels as failures.
What the computer is actually seeing
The engine control module (ECM) sees a coolant temp reading from the sensor, which should typically range between 185°F to 220°F (85°C to 104°C) when the engine is operating normally. A reading above or below these thresholds triggers the fault code.
What a healthy reading looks like
Normal coolant temperature readings should be between 185°F to 220°F (85°C to 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.
- 1Check coolant level in the reservoir. Must be between low and high marks. Decision: If coolant is low, refill and monitor for leaks. If not low, proceed to step 2.
- 2Inspect the wiring and connector for the coolant temperature sensor for damage, corrosion, or loose connections. Decision: If damaged, repair or replace. If not, proceed to step 3.
- 3Use a scan tool to check the current engine coolant temperature reading. Compare with actual temperature using an infrared thermometer at the sensor location. Decision: If there is a significant difference (more than 10°F/5°C), replace the coolant temperature sensor. If readings are close, verify the function of the thermostat.
Common causes
- Faulty coolant temperature sensor
- Wiring damage or connector issues
- Low coolant level or leaks
- Thermostat stuck closed or open
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to address this ASAP as overheating can cause serious engine damage.
Will the code come back after repairs?
If repairs are done correctly, the code should not reappear.
Why does this code sometimes pair with SPN 11?
SPN 11 is for the coolant level sensor, so both can trigger due to coolant issues.
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