U01BB code meaning
Lost Communication With Battery Charger Control Module B
What U01BB means
Battery charger control module B is, by its name, a second on-board charger, as fitted on some electric cars to raise AC charging power. Polestar uses the code differently: Technical Journal 37630 (2026, vehicle type 359 from model year 2025) lists U01BB00 in the central computer GCCC when its only AC charger, the grid-to-HV converter GHCA, has failed. In that case AC charging stops while DC fast charging still works, and the converter is diagnosed and replaced. So the letter does not always mean a physical second unit. CARB 1968.2 makes plug-in vehicles responsible for spotting charger faults that block charging or reduce its rate. Expect a charging fault message and no AC charging; U019B and U027A cover chargers A and C, U04BE invalid data from B.
U01BB at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U01BB
- AC charging impossible while DC fast charging works
- Charging fault message or charge port LED error
Common causes of U01BB
- Most likelyOn-board charger unit failed (Polestar GHCA replaced)
- PossibleCharger without 12 V supply, ground or wake-up signal
- Less likelyBus wiring or connector at the charger damaged
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
On board chargerCAN bus
What each part of U01BB means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| BB | The exact fault in that area. |
What to do next
- Note U01BB and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U01BB
What does U01BB mean?
U01BB means "Lost Communication With Battery Charger Control Module B". Battery charger control module B is, by its name, a second on-board charger, as fitted on some electric cars to raise AC charging power. It is a generic code, so it means the same on every make.
Is it safe to drive with U01BB?
U01BB does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U01BB fail an emissions test?
U01BB is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U01BB to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U01BB clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.