P05F6
Exhaust Aftertreatment Power Relay Control Circuit Stuck On
The aftertreatment power relay is stuck on - aftertreatment electronics stay powered after key-off, draining the battery.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Relay welded closedCommon
- Carbon or debris buildup preventing free movementLess likely
- Component wear with age - mechanical playLess likely
Parts involved
- Aftertreatment Power Relay
P05F6 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.