OBD-II code · Network
U028A Lost Communication With Transmission Fluid Pump Module B
The vehicle bus reports loss of communication with transmission fluid pump module B. Auxiliary ATF pumping during start/stop or hybrid coast cannot be commanded, which may delay shifts or impair cooling.
Is it safe to drive with U028A?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Transmission Fluid Pump Module B, Vehicle Bus Wiring
Related codes
- U0287Lost Communication With Transmission Fluid Pump Module A
- U0288Lost Communication With DC/AC Converter Control Module A
- U0289Lost Communication With DC/AC Converter Control Module B
- U028BLost Communication With Active Grille Air Shutter Module C
- U028CLost Communication With Active Grille Air Shutter Module D
- U028DLost Communication With Active Aerodynamic Feature Control Module A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.