P27E1Electric/Auxiliary Transmission Fluid Pump A Pressure Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P27E1 is a hydraulic verdict, not a wiring one: electric auxiliary pump A was running on command, yet the pressure it built stayed below what the module expected. No manufacturer documents this exact code publicly. GM shows how such a check works on its CVTs (2025 TCM tables): during an engine auto-start, with more than 400 kPa requested, both pulley pressure sensors reading under 200 kPa for over 0.525 s set the broader performance code P2797, Type B. Wiring faults on the pump belong to P2796 and its siblings, leakage to P0B0C, and pump B has P27E2. Worn pump gears, a clogged intake screen, low fluid or a leaking check valve are typical. Stop-start is usually blocked, and restarts after a stop may engage harshly.
- What you may notice
- Stop-start function disabled
- Jerky or delayed engagement when the engine restarts after a stop
- MIL or transmission warning lit
- Likely causes
- LikelyWorn pump gears or internal leakage inside pump A
- PossibleLow or aerated transmission fluid, pump draws air
- PossibleIntake screen of the pump partly blocked by debris
- RareCheck valve in the pump circuit not sealing
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.