Engine Coolant Temperature Sensor High
The engine coolant temperature sensor is reading higher than expected.
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What it means (plain English)
The engine coolant temperature sensor measures how hot the coolant is. If it reads too high, it means there's an issue like a stuck thermostat, bad sensor, or a problem with the wiring.
What the computer is actually seeing
The Engine Control Module (ECM) sees a coolant temperature reading above the normal operating range, typically over 230°F (110°C) when the engine is not overheating.
What a healthy reading looks like
Coolant temperature should normally range between 190°F (88°C) to 220°F (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. Is it low? -> If yes, fill it and check for leaks.
- 22. Inspect the wiring and connector to the coolant temperature sensor. Any signs of damage or corrosion? -> If yes, repair or replace as necessary.
- 33. Use a scan tool to read the coolant temperature data. Is it reading above 230°F (110°C)? -> If no, sensor may be faulty.
- 44. Confirm the thermostat operation by feeling the upper radiator hose. Is it hot indicating flow? -> If no, replace the thermostat.
Common causes
- Faulty coolant temperature sensor
- Wiring issue or short to voltage
- Stuck thermostat (staying closed)
- Low coolant level or airflow restrictions
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It’s generally safe to drive, but monitor coolant temperature closely. Overheating can lead to engine damage.
Will this code come back after clearing?
If the issue isn't fixed, it will likely return after a short drive cycle.
Why does this code pair with SPN 871?
SPN 871 indicates the coolant sensor voltage is out of range, which often correlates with SPN 872 high temperature readings.
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