P20D8
Exhaust Aftertreatment Fuel Supply Control Performance
Aftertreatment fuel supply is electrically OK but does not deliver the commanded pressure or flow during regeneration — weak pump or partial blockage.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Pump weak — flow or pressure below thresholdCommon
Parts involved
- Aftertreatment Fuel Pump
P20D8 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.