Reductant Temperature Sensor Circuit High
The sensor measuring the temperature of the diesel exhaust fluid is showing a high voltage reading.
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What it means (plain English)
Inside the DEF system, this code means the sensor that checks how hot the diesel exhaust fluid (DEF) is, is sending a voltage that’s too high, often over 5 volts — indicating a potential short circuit.
What the computer is actually seeing
The engine control module (ECM) detects a voltage level from the reductant temperature sensor that exceeds its acceptable range, typically above 5 volts.
What a healthy reading looks like
Reductant temperature should be between 0 and 90 degrees Celsius; the voltage output from the sensor is usually between 0.5 to 4.5 volts at normal operational temperatures.
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 connector to the reductant temperature sensor for damage or corrosion. If you find any issues, repair or replace as necessary (decision point: is the wiring intact?).
- 22. Measure the voltage at the sensor connector with the ignition on and the engine off. If the voltage is over 5 volts, continue to step 3 (decision point: is the voltage normal?).
- 33. Disconnect the reductant temperature sensor and measure the resistance across the sensor terminals. It should vary with temperature; if it’s open or shorted, replace the sensor (decision point: is the sensor faulty?).
- 44. Check the DEF quality and ensure it’s not contaminated. Replace with new DEF if needed (decision point: is the DEF fluid contaminated?).
- 55. If all previous checks are okay and the code returns, suspect the ECM as a potential cause and carry out further diagnostics.
Common causes
- Shorted sensor wiring
- Faulty reductant temperature sensor
- Faulty ECM
- Contaminated or damaged DEF fluid
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive with this code?
Yes, but it's advisable to fix it soon to avoid potential emissions issues.
Will this code come back after a reset?
It might if the underlying issue isn't resolved.
Why does this code pair with related codes?
These codes typically relate to the DEF system and its components.
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