Reductant Performance - Insufficient Quality
The engine control module detects a problem with the quality of the reductant (DEF) being used.
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)
The computer is saying the diesel exhaust fluid (DEF) isn't good enough to reduce emissions, which can cause issues with the exhaust system.
What the computer is actually seeing
The engine control module (ECM) evaluates the cleanliness and quality of the DEF based on feedback from sensors. If it notices that the DEF contains too many contaminants or doesn’t meet the required quality thresholds, it triggers this code.
What a healthy reading looks like
DEF quality should be above 32.5% urea concentration; anything lower may trigger the code.
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 DEF quality. Make sure it’s a good brand and meets ISO 22241 standards.
- 22. Inspect the DEF tank and lines for contamination or blockages. If contaminated, flush and refill with quality DEF.
- 33. Test the DEF quality sensor with a multimeter. Typical operation values are between 0.5V and 4.5V depending on quality. Reference the specific schematic for your vehicle.
- 44. Clear the code and perform a road test to see if it returns. If it comes back, further diagnosis on the DEF injector and ECM may be needed.
Common causes
- Poor quality DEF being used
- DEF contamination from improper storage
- Blocked or damaged DEF injector
- Faulty DEF quality sensor
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive long distances as it may go into limp mode, reducing power and emissions.
Will this code come back after clearing it?
Yes, if the quality issue isn’t resolved and the DEF remains contaminated, it will likely reappear.
Why does this code sometimes pair with other codes?
This often happens because several faults can be related to DEF quality issues or the exhaust aftertreatment system.
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