P2A8F
Alternative Fuel Pump B Performance
The AFCM detects that alternative fuel pump B does not produce the expected pressure or flow for the commanded duty. Pump aging, internal leakage, or supply restriction.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Symptoms
- Check engine light on
- Hard start, no start, or stalling under load
- Power loss especially at high load or rpm
- Possible long cranking time
Common causes
Ordered by how often each turns out to be the cause.
- Pump internal wear reduces outputCommon
- Fuel filter cloggedPossible
Parts involved
- Alt Fuel Pump B
- Alt Fuel Filter
P2A8F 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.