Reductant Quality Sensor Range/Performance Problem
The reductant quality sensor is reporting a range or performance issue.
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What it means (plain English)
The reductant quality sensor measures the quality of the diesel exhaust fluid (DEF) being used. If it thinks the fluid isn't good enough, the engine might reduce power to prevent damage.
What the computer is actually seeing
The engine control unit (ECU) sees values from the reductant quality sensor that are outside specified ranges, indicating the DEF may be contaminated or improperly mixed.
What a healthy reading looks like
Typically, the reductant quality sensor should output a voltage between 0.5V (bad DEF) to 4.5V (good DEF), with a defined range for acceptable DEF quality.
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 DEF fluid level—should be full and clean.
- 22. Check DEF quality—should be clear and free of contaminants, no colored or abnormal substance present.
- 33. Use a multimeter to measure the output voltage of the reductant quality sensor; it should be within 0.5V to 4.5V.
- 44. Inspect the wiring and connector for damage or corrosion—repair or replace as necessary.
- 55. If the sensor checks out and fluid is good, replace the reductant quality sensor.
Common causes
- Contaminated diesel exhaust fluid (DEF)
- Failed reductant quality sensor
- Wiring issues or short circuits in the sensor circuit
- Poor connection at the sensor connector
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's safe to drive, but power may be reduced, and the vehicle may not be allowed to enter regen mode.
Will the code come back after clearing?
It can come back if there's a persistent issue with the DEF or the sensor itself.
Why does this code appear with some other codes?
It often pairs with other reductant quality or DEF system codes, indicating a systemic issue.
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