U027ALost Communication With Battery Charger Control Module C
- Generic OBD-II code · Network
- How the car detects it
- Module C is a third on-board charger in the same vehicle; A and B have U019B and U01BB. Several chargers on one bus need clearly separated roles, and a Lear patent shows one way: each unit reads a coded input at start-up, then joins the vehicle bus either as master with the master message set or as slave with the slave set. A slave whose input or wiring is wrong can thus vanish from the network. U027A is stored when the supervising controller stops hearing charger C. No manufacturer documents the code publicly or names a third charger. For plug-in hybrids CARB only asks for detection of charger faults that stop charging or reduce the charging rate. AC charging then usually runs slower; driving and emissions are not affected.
- What you may notice
- Reduced AC charging power or longer charging time
- Charging fault message
- Likely causes
- Likely12 V supply or wake-up line of charger C missing
- PossibleBus connector at charger C corroded or not latched
- PossibleCharger C coded or addressed wrongly after replacement
- RareCharger C control electronics faulty
- Repair
- Hard · Usually a job for a workshop.Typical cost: €0 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.