P28ED — Electric/Auxiliary Transmission Fluid Pump B Overspeed
The auxiliary transmission fluid pump B exceeds the calibrated maximum speed for the commanded duty. Mechanical load on the pump unexpectedly low.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Aux transmission pump b
- Transmission fluid
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Pump impeller damage - load lost
- Aerated fluid - reduced load
Possible 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
Diagnostic notes
- The malfunction indicator lamp may illuminate
- Reduced-power or limp mode may occur
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.