Powertrain
generic / SAE
P277A
Electric/Auxiliary Transmission Fluid Pump B Hydraulic Leakage
The second auxiliary transmission fluid pump cannot maintain pressure even at high duty cycle. Indicates internal hydraulic leakage downstream of the pump.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number7 / 7A
Possible causes
- Worn or hardened seals downstream of pump high
- Pressure relief or bypass valve stuck open 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
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 400–3000 €
- Estimated time: 3–8 h
- Component: aux trans pump b
- Component: hydraulic circuit
- Component: valve body seals
- MIL / check engine light
Sources
References
sae:J2012