Coolant Temperature Sensor Signal Range/Performance Problem
The engine control module (ECM) detects a problem with the coolant temperature sensor signal.
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What it means (plain English)
The ECM is having trouble getting a clear signal from the coolant temperature sensor, which tells it how hot the engine is running, usually sending a voltage between 0.5V (cold) to 4.5V (hot).
What the computer is actually seeing
The ECM expects a voltage signal corresponding to specific temperatures; if the sensor sends a voltage that is too low or too high for too long, it triggers this code.
What a healthy reading looks like
Expected voltage values from the coolant temperature sensor should range from 0.5V to 4.5V, correlating with temperatures from around -40°F to 260°F.
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 and condition. Top off if low and replace if contaminated. Decision Point: If coolant is low, fill and test. If not low, proceed.
- 22. Inspect the wiring and connector at the coolant temperature sensor. Look for frays, corrosion, or looseness. Decision Point: If wiring is damaged, repair/replace; if good, proceed.
- 33. Use a multimeter to test the voltage at the coolant temperature sensor connector with the engine running. Expected range is 0.5V to 4.5V. Decision Point: If voltage is out of range, replace the sensor; if in range, proceed.
- 44. Check the ECM for stored codes for additional faults. If codes are related and indicate sensor issue, proceed with ECM diagnostics.
Common causes
- Faulty coolant temperature sensor
- Wiring issues (loose or corroded connectors)
- Shorted or open circuits in the sensor harness
- Coolant level low or poor contact at the connector
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's safe to drive, but monitor engine temperature; fix soon to prevent overheating.
Will the code come back after repair?
If the underlying problem is fixed, the code should not return.
Why is this paired with other temperature codes?
Multiple codes can occur when there's a common fault affecting temperature readings.
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