OBD-II code · Powertrain (generic, extended)
P20FB Reductant Pump B Control Performance/Stuck Off
DEF pump B receives a run command but does not start, or shuts off prematurely.
Is it safe to drive with P20FB?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyPump head crystallised — motor seized
- Less likelyCarbon or debris buildup preventing free movement
- Less likelyComponent wear with age - mechanical play
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)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–3.5 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Pump
Related codes
- P208BReductant Pump A Control Performance/Stuck Off
- P20FAReductant Pump B Control Circuit/Open
- P20F8Intake Manifold Runner Control Circuit Performance (Bank 1)
- P20F9Intake Manifold Runner Control Circuit Performance (Bank 2)
- P20FCReductant Pump B Control Circuit Low
- P20FDReductant Pump B Control Circuit High
- P20FEReductant Metering Unit 1 Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.