P27A3
Electric/Auxiliary Transmission Fluid Pump B Performance/Stuck Off
The second auxiliary transmission fluid pump is commanded on but does not run.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
Ordered by how often each turns out to be the cause.
- Pump motor seized by sedimentCommon
- Cracked rotor magnet decouples drivePossible
- Carbon or debris buildup preventing free movementLess likely
Parts involved
- Aux Trans Pump B
- Pump Motor
P27A3 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.