Engine Coolant Temperature Sensor
Indicates an issue with the engine coolant temperature sensor circuit.
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 computer measures how hot the engine coolant is with a sensor. If that sensor is broken or the wiring is faulty, the computer doesn't know if the engine is too hot or too cold.
What the computer is actually seeing
The engine control module (ECM) monitors the voltage signal from the coolant temperature sensor, expecting to see a range of about 0.5 to 4.5 volts corresponding to temperatures from -40°F to 248°F (-40°C to 120°C).
What a healthy reading looks like
Voltage around 0.5V (cold) to 4.5V (hot), resistance of sensor should be about 3,000 ohms at 75°F (24°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 the coolant level; top off if necessary and see if code returns. Decision: If the coolant is low, refilling may solve issue. If not, proceed to step 2.
- 22. Inspect the wiring and connectors to the coolant temperature sensor for damage or corrosion. Decision: If any issues found, repair or replace them and retest. If no issues found, proceed to step 3.
- 33. Test the coolant temperature sensor with a multimeter. Check resistance at known temperatures. Decision: If resistance doesn’t match expected values, replace the sensor. If it does, proceed to step 4.
- 44. Use a scan tool to check the live data for the coolant temperature; compare to actual engine temperature. Decision: If readings are drastically different, the ECM may need to be tested.
Common causes
- Faulty coolant temperature sensor
- Wiring harness shorts or opens
- Corroded or loose connector pins
- ECM software issues
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; you can drive but should fix it soon as it can lead to overheating issues.
Will this code come back after clearing?
If the underlying issue isn't resolved, yes, it likely will return.
Why does this code sometimes pair with other codes?
It can indicate a broader electrical system issue, affecting multiple sensors. Check all related codes.
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