OBD-II code · Powertrain (generic, extended)
P27A1 Electric/Auxiliary Transmission Fluid Pump A Stuck On
The first auxiliary transmission fluid pump runs even when no command is active.
Is it safe to drive with P27A1?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyTCM output driver stuck on
- PossibleControl wire shorted to a permanent B+ supply
- Less likelyCarbon or debris buildup preventing free movement
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
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.8–3.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Aux Trans Pump A, Control Module, Wiring Harness
Related codes
- P27A6Electric/Auxiliary Transmission Fluid Pump B Stuck On
- P279EFour Wheel Drive (4WD) Range Signal Circuit Range/Performance
- P279FFour Wheel Drive (4WD) Range Signal Circuit Low
- P27A0Four Wheel Drive (4WD) Range Signal Circuit High
- P27A2Electric/Auxiliary Transmission Fluid Pump B Control Circuit / Open
- P27A3Electric/Auxiliary Transmission Fluid Pump B Performance/Stuck Off
- P27A4Electric/Auxiliary Transmission Fluid Pump B Control Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.