Reductant Quality Error
This code indicates a problem with the quality of the diesel exhaust fluid (DEF).
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
Your truck measures the quality of the DEF, which is supposed to help clean the exhaust. If it sees something wrong, it throws this code.
What the computer is actually seeing
The engine control module (ECM) checks the conductivity and quality of the DEF using a sensor. If the readings fall outside the acceptable range, it triggers this fault code.
What a healthy reading looks like
The conductivity of DEF should be between 5.0 and 7.0 mS/cm. If it measures below or above this range, the code will be set.
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.
- 1Check the quality of the DEF; it should be clear and free of contamination. If it looks murky or has particles, replace it.
- 2Inspect wiring and connectors for the DEF quality sensor for damage or corrosion. Repair if needed.
- 3Test the DEF quality sensor with a multimeter; it should show conductivity values between 5.0 and 7.0 mS/cm. If it's outside this range, replace the sensor.
- 4If the sensor and DEF are okay, check the SCR system for any faults that could affect sensor readings.
Common causes
- Contaminated diesel exhaust fluid (DEF)
- Faulty DEF quality sensor
- Wiring issues in the DEF sensor circuit
- Defective SCR (Selective Catalytic Reduction) system
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally drivable, but you may notice reduced power and efficiency until it's fixed.
Will this code come back after I clear it?
If the underlying issue isn't resolved, yes, it will return.
Why do I see this code with other DEF-related codes?
They often overlap because they all relate to the same system and its components.
Working a real vehicle right now?
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