Engine Temperature Signal Invalid
The engine temperature sensor signal is out of range or missing.
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What it means (plain English)
The computer expects a certain temperature from the engine temperature sensor but gets a reading that's way off, possibly because the sensor is broken or there's a wiring issue.
What the computer is actually seeing
The ECM is monitoring the engine temperature from the sensor, typically a voltage signal in the range of 0.5V to 4.5V corresponding to temperatures from about -40°C to 125°C. A reading outside this range or no reading at all triggers the fault.
What a healthy reading looks like
Voltage should be between 0.5V (around -40°C) and 4.5V (around 125°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 engine temperature sensor wiring for damage or shorts. Repair any issues found.
- 22. Inspect the connector at the engine temperature sensor for corrosion or poor connection. Clean or replace as necessary.
- 33. Use a scan tool to monitor the engine temperature signal while the engine is running. Verify it corresponds to the actual engine temperature. If signal is missing, go to step 4, if signal is correct, suspect ECM issue.
- 44. Replace the engine temperature sensor and clear the codes. Retest the system.
Common causes
- Faulty engine temperature sensor
- Wiring harness issue (short or open circuit)
- Connector corrosion or damage
- ECM software issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally safe to drive, but monitor the temperature gauge closely and fix the code soon to avoid potential overheating issues.
Will the code come back after fixing?
If the underlying issue is resolved (like a bad sensor or wiring), it shouldn't return.
Why does this code appear with other codes?
Sensor failures often affect multiple readings; if one sensor fails, related sensor codes may appear as a result.
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