U0337 indicates a software mismatch between the battery charger control module and the vehicle’s engine control unit. The modules cannot communicate properly, usually because their firmware versions are incompatible.
The module’s software is newer or older than the engine control unit’s firmware, preventing proper handshake.
The engine control unit’s software was updated without updating the battery charger module, causing a compatibility gap.
Physical damage or internal failure can mimic a software incompatibility signal even if firmware is correct.
A broken or shorted CAN bus connection between the modules can trigger a software compatibility error.
Non‑OEM modules may not be designed to work with the vehicle’s engine control unit firmware.
Rarely, the engine control unit’s firmware may be corrupted, leading to a false incompatibility message.
Replacing the engine control unit is usually unnecessary and not the correct fix for a software incompatibility code. The root cause is typically a mismatch or fault in the battery charger control module or its firmware.
No. U0337 specifically indicates a communication/software issue between the battery charger control module and the engine control unit, not a battery health problem.
Yes, updating the firmware on both the battery charger control module and the engine control unit to compatible versions is the standard resolution.
If the module is found to be damaged or its firmware cannot be updated to match the engine control unit, replacement is the appropriate action.