Engine Exhaust Temperature Sensor Circuit Low
The engine's exhaust temperature sensor is reporting a lower voltage than expected.
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What it means (plain English)
The exhaust temperature sensor measures the heat in the exhaust system, and when it sends a signal that's too low, the engine fears it could be malfunctioning or there’s a wiring issue causing the problem.
What the computer is actually seeing
The Engine Control Unit (ECU) expects the exhaust temperature sensor to output a voltage range of approximately 0.5 to 2.5 volts, depending on the temperature it detects (typically between 100°C to 600°C). When it sees a voltage lower than 0.5 volts, it triggers the code.
What a healthy reading looks like
Exhaust temperature sensor should output between 0.5V (100°C) and 2.5V (600°C) in normal operation.
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. Inspect the wiring and connectors at the exhaust temperature sensor for damage or corrosion. Fix as necessary. Decision Point: Did you find any issues? If yes, repair them and retest. If no, proceed to step 2.
- 22. Measure the voltage at the exhaust temperature sensor connector with the ignition on but the engine off. Expected voltage should be between 0.5V to 2.5V. Decision Point: Is the voltage reading below 0.5V? If yes, replace the sensor. If no, proceed to step 3.
- 33. Check the ground connection for the exhaust temperature sensor. Use a multimeter to verify continuity to the negative battery terminal. Decision Point: Is there good continuity? If no, fix the ground issue. If yes, the problem may lie in the ECU.
Common causes
- Faulty exhaust temperature sensor
- Wiring issues or shorts in the sensor circuit
- Connector problems or corrosion at the sensor plug
Typical repair cost
$$
Related codes
Frequently asked questions
Can I still drive the vehicle with this code?
Yes, but it’s recommended to fix soon to avoid potential emissions issues or other diagnostic trouble codes.
Will this come back after I clear it?
If the underlying issue (sensor or wiring) isn't fixed, yes, it will likely return.
Why does this code appear with SPN 3708?
SPN 3708 relates to the same exhaust temperature sensor circuit, indicating multiple faults or issues.
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