OBD-II trouble code
U0339: Software Incompatibility With Body Control Module 'B'
A module has detected that body control module B — the second of two body electronics controllers on vehicles with split BCM architecture — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $130 – $550
- DIY difficulty
- Shop recommended
What does U0339 mean?
U0339 is the 'B' sibling of U0331 (Body Control Module 'A') in the software-incompatibility family. Some vehicles, especially those with a large number of body electronics functions, split body control duties across two modules to manage the workload — for example, one BCM handling lighting, locks, and windows while a second handles comfort, convenience, or interior features. U0339 sets when a module on the network determines that body control module B is running a software or calibration version that is incompatible with the version-matched set the rest of the vehicle expects. Manufacturers release these paired BCM calibrations as a coordinated set so that shared inputs — door status, ignition state, ambient light, and similar signals — are interpreted consistently by both modules. When module B's software doesn't fit that set, U0339 is stored — the modules are still communicating, but they disagree about which software body control module B should be running.
The cause is almost always service-related and centered on body control module B. It was replaced (including with a used or salvage unit) and not programmed with the correct VIN-specific software, a software update was applied to body control module A or another module but not module B, or a reflash was interrupted or used the wrong calibration file. Because the underlying issue is data rather than a failed switch, relay, or wiring harness, chasing it electrically leads nowhere — the fix is reprogramming body control module B to a matching, manufacturer-approved software set.
Because body control module B typically governs a mix of comfort and convenience features rather than safety-critical systems, U0339 is generally rated medium severity, similar to its 'A' counterpart. Symptoms depend heavily on exactly which functions this particular module controls on the vehicle in question — common results include interior lighting, power windows/locks, seat memory, or convenience feature glitches. The vehicle should continue to start, drive, and brake normally. Still, address it in a timely way, since body control functions sometimes overlap with security (locking) or visibility (lighting) features that are worth restoring promptly.
Common causes
- Body control module B replaced without correct VIN-specific programming
- A used or salvage-yard body control module B installed without being re-learned to this vehicle
- Body control module A or another module's software updated but module B's calibration left out of step
- An interrupted or incomplete body control module B reflash
- Reprogramming done with the wrong calibration file or trim/feature-set variant
- Mismatched hardware/software part numbers after body electronics service
Symptoms
- Warning message and a stored U0339 (often alongside U0322, U0331, or other U03xx codes)
- Interior/exterior lighting, power window, or power lock features not working correctly
- Seat memory, mirror, or other body-electronics convenience features malfunctioning
- Intermittent or inconsistent behavior of features controlled by this module
- Condition typically appears right after a body control module replacement, update, or reflash
Diagnostic steps
- 1.Confirm the recent history — U0339 almost always follows a body control module replacement, software update, or reflash; identify what was serviced.
- 2.Scan all modules and read body control module B's software/calibration part number; compare against the manufacturer's current approved set for the VIN.
- 3.Note any companion codes (e.g. U0300, U0322, U0331) that help confirm module B is the mismatched module.
- 4.Identify which specific functions this vehicle assigns to body control module B, and test those functions to characterize the symptoms.
- 5.Verify the module was programmed with correct VIN-specific software, not generic or wrong-trim data.
- 6.Reprogram/reflash body control module B to the matching, up-to-date calibration using a manufacturer-approved tool.
- 7.Clear the codes and confirm U0339 does not return and affected features work correctly after a full key cycle.
Repair cost
$130 – $550
This is a programming fix, not a parts fix. Reprogramming body control module B typically runs $130-$350, and up to $550 when dealer-only calibrations or multiple related modules need to be reprogrammed together. If the module was wrongly replaced, the prior repair is the real expense; U0339 itself is usually resolved by correct reprogramming rather than buying more hardware.
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DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.