P27E1
Electric/Auxiliary Transmission Fluid Pump A Pressure Too Low
The auxiliary transmission fluid pump A produces less pressure than expected for the commanded duty. Pump aging, leakage, or fluid loss.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
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
Common causes
Ordered by how often each turns out to be the cause.
- Pump worn or leaking internallyCommon
- Transmission fluid level lowPossible
Parts involved
- Aux Transmission Pump A
- Transmission Fluid
- Valve Body
P27E1 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.