U0297 code meaning
Lost Communication With AC/DC Converter Control Module B
Network system Generic code U02xx codes Check engine light
What U0297 means
Converter B is a second AC/DC unit, typically an additional on-board charger that raises AC charging power when combined with the first. Patents show how such pairs are coordinated: in Porsche's US10029578B2 one charger leads and the other follows commands received over a communication link, while Hyundai's US10270273B2 has a master controller steering slave controllers for several power modules. U0297 is stored when the controlling module no longer hears unit B. The vehicle usually continues to charge with converter A alone, but at a lower rate. Because CARB wants plug-in hybrid OBD to catch charger problems that reduce charging speed, a silent B is relevant there too. No manufacturer documents U0297 publicly; Volvo's use of U0296 concerns unit A.
U0297 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0297
- AC charging noticeably slower than usual
- Charging system warning
Common causes of U0297
- PossibleLow-voltage supply or wake-up line of charger B missing
- PossibleCommunication line between the converters interrupted
- PossibleSoftware or configuration does not match the fitted charger variant
- Less likelyConverter B internally failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ac dc converter module bVehicle bus wiring
What each part of U0297 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 97 | The exact fault in that area. |
What to do next
- Note U0297 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 U0297
What does U0297 mean?
U0297 means "Lost Communication With AC/DC Converter Control Module B". Converter B is a second AC/DC unit, typically an additional on-board charger that raises AC charging power when combined with the first. It is a generic code, so it means the same on every make.
Is it safe to drive with U0297?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U0297 fail an emissions test?
Yes, it can. U0297 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0297 to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will U0297 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.