P208B
Reductant Pump A Control Performance/Stuck Off
DEF pump A receives a run command but does not start, or shuts off prematurely — pump performance is below threshold.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
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)
Common causes
Ordered by how often each turns out to be the cause.
- Pump motor seized — DEF crystallised inside pump headCommon
- Motor brushes wornPossible
- Carbon or debris buildup preventing free movementLess likely
Parts involved
- Reductant Pump
P208B is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.