What it means
DEF pump A current draw exceeds the upper threshold — typically a seized pump head or partial winding short.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Reductant pump A moves DEF (AdBlue) through the selective catalytic reduction system so the exhaust can be treated to reduce nitrogen oxides. The controller monitors pump A’s electrical current and sets this code when the draw exceeds its upper limit, which can happen if the pump binds or its winding is partly shorted.
Common causes
Most likely first.
- Pump head seized
- Winding partially shorted
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Save freeze-frame data and check SCR, DEF pressure, pump, and NOx codes to see whether the high current occurred during a pump command.
- Use scan-tool data to compare commanded pump operation, current, and reductant pressure where available.
- Inspect pump A’s connector and wiring for corrosion, fluid intrusion, damaged insulation, or a short that could affect measured current.
- Check DEF condition and the pump or line for contamination, freezing, blockage, or mechanical binding using the manufacturer’s procedure.
- If wiring and flow are sound, test pump A’s current draw and operation against the manufacturer’s specification.
Common fixes
- Repair a damaged or shorted pump A wire or connector.
- Correct a frozen, contaminated, or obstructed DEF supply if found.
- Replace pump A if it binds or draws excessive current during the specified test.
- Clear the code and verify pump operation and reductant delivery.
Can I keep driving?
The vehicle may remain drivable initially, but emissions control can fail and some vehicles start a no-start countdown if the DEF fault is ignored. Arrange repair soon and follow any dashboard countdown or operating restriction.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.