Powertrain
generic / SAE
P205F
Reductant System Performance (Bank 2)
The DEF system as a whole on bank 2 is not delivering the required NOx reduction — NOx-out remains too high relative to commanded dosing across a drive cycle. Causes range from poor DEF quality, restricted dosing line, weak pump, to a degraded SCR catalyst.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / 5F
Possible causes
- Poor DEF quality — diluted or contaminated high
- SCR catalyst thermally aged medium
- Crystallisation restricts dosing line 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)
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 200–4000 €
- Estimated time: 1.5–8 h
- Component: scr catalyst
- Component: reductant metering unit
- Component: reductant quality sensor
- Component: reductant pump
- MIL / check engine light
- emissions-relevant
- drive cycle required
- limp mode possible
Sources
References
sae:J2012