OBD-II code · Powertrain (generic, extended)
P27A5 Electric/Auxiliary Transmission Fluid Pump B Control Circuit High
Voltage on the second auxiliary transmission fluid pump control line is above the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P27A5?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl wire shorted to B+
- PossibleOpen motor winding
- Less likelyConnector pins corroded - high contact resistance
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 B, Wiring Harness
Related codes
- P2799Electric/Auxiliary Transmission Fluid Pump A Control 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
- P27A6Electric/Auxiliary Transmission Fluid Pump B Stuck On
- P27A7Pressure Control Solenoid A Data Incompatible
- P27A8Pressure Control Solenoid B Data Incompatible
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.