Cooling System Temperature Sensor Out of Range
The ECM detected a cooling system temperature that is outside the expected range.
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 Control Module (ECM) expects the coolant temperature to be between 175°F and 220°F when the engine is running. If the temperature is too high or too low, it triggers this fault code.
What the computer is actually seeing
The ECM sees a coolant temperature reading from the sensor that is either significantly above 220°F or below 175°F, which is out of the normal operating range.
What a healthy reading looks like
Coolant temperature should typically range between 175°F and 220°F under normal operating 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 reservoir. Ensure it's within the proper range. If low, refill and recheck for code. Decision: If code clears, the issue was low coolant. If not, proceed to step 2.
- 22. Inspect the wiring and connector at the coolant temperature sensor for damage or corrosion. Use a multimeter to test for continuity. Decision: If wiring is bad, repair it. If wiring is good, proceed to step 3.
- 33. Test the coolant temperature sensor with a multimeter. At a known temperature (use boiling water for 212°F), the sensor should read approximately 0.5V. Check the specifications for your specific sensor. Decision: If sensor is out of range, replace it. If sensor is within range, proceed to step 4.
- 44. Use a scan tool to monitor the coolant temperature while the engine is running. Compare the reading to the actual temperature with a thermometer. Decision: If the readings match and the fault persists, consider testing the ECM.
Common causes
- Faulty cooling system temperature sensor
- Wiring issues between the sensor and ECM
- Coolant leaks or low coolant level
- Thermostat stuck open or closed
- Faulty ECM
Typical repair cost
$$-$$$$ (varies based on parts needed)
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's not recommended to drive too long with this code due to potential overheating. Fix it as soon as possible.
Will this problem come back?
If the underlying issue is not resolved, it can definitely recur after clearing.
Why does this code show up with other codes?
This code can be triggered alongside others due to common underlying issues, like a faulty sensor or wiring problems affecting multiple systems.
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