U0339 code meaning
Software Incompatibility With Body Control Module B
What U0339 means
Body control module B is a second body controller that takes over part of the switching, for example in a rear or auxiliary junction box. U0339 means a partner module rejects its software or setup; U0331 covers unit A, U0322 vehicles with a single body controller. Jaguar uses exactly this name: on the 2010 XF 5.0 V8 and the 2010–2011 XK, the auxiliary junction box, listed as body control module B, could drop the fuel pump relay after start, so the engine stalled once the high-pressure pump ran short; recall J017 loaded revised software and reconfigured that box. Ford has a BCM-B on 2022–2023 Mustang Stealth models, where a wrong configuration left the sill plates dark until program 23B60 reconfigured it with FDRS. U0142 is lost contact, U0443 invalid data. Usually no MIL.
U0339 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0339
- Functions switched by the second body module fail, such as lights or sill plate illumination
- Depending on its tasks, engine may stall or not start
- Network codes in several modules after body module work
Common causes of U0339
- Most likelyBody control module B carries a configuration that does not match the vehicle
- PossibleUnit B left on an older software level after an update campaign
- Less likelyAuxiliary junction box replaced without programming
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Body control module b
What each part of U0339 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 39 | The exact fault in that area. |
What to do next
- Note U0339 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 U0339
What does U0339 mean?
U0339 means "Software Incompatibility With Body Control Module B". Body control module B is a second body controller that takes over part of the switching, for example in a rear or auxiliary junction box. It is a generic code, so it means the same on every make.
Is it safe to drive with U0339?
U0339 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0339 fail an emissions test?
U0339 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 U0339 to fix?
Difficulty: workshop only. A typical repair takes 0.3 to 2 hours of work. This is a job for a workshop.
Will U0339 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.