Powertrain
generic / SAE
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.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number7 / A5
Possible causes
- Control wire shorted to B+ high
- Open motor winding medium
- Connector pins corroded - high contact resistance low
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
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 180–1000 €
- Estimated time: 0.8–3.5 h
- Component: aux trans pump b
- Component: wiring harness
- MIL / check engine light
Sources
References
sae:J2012