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DTC codes / U03xx · Software and configuration mismatches / U0337

U0337Software Incompatibility With Battery Charger Control Module A

U0337 is a network communication fault indicating that one control module has received data from the battery charger control module (module A) that is incompatible with its own software or configuration. The computer detected a mismatch in software version, calibration, or message format between the two modules, so it flags the battery charger control module as incompatible rather than reporting a hardware failure.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaSoftware and configuration mismatches

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) or a dedicated service warning light
  • Often no symptoms besides the warning light, with the vehicle driving normally
  • Battery charging system warning message or icon displayed on the dash
  • Reduced or disabled battery charging functionality, especially on hybrid or electric vehicles
  • Intermittent electrical accessories or module communication glitches
  • Remote start or power management features may be inoperative

Common causes, most likely first

  1. Battery charger control module has an outdated or incorrect software calibration installed
  2. A control module on the network was replaced or reprogrammed without matching software versions
  3. Corrupted or incomplete software flash during a previous reprogramming event
  4. Aftermarket or non-OEM battery charger control module installed with incompatible firmware
  5. Low voltage or power interruption during a module programming session causing configuration mismatch
  6. Faulty CAN (Controller Area Network) wiring or connectors causing corrupted messages that the receiving module interprets as incompatible
  7. Internal fault in the battery charger control module preventing it from reporting a compatible software identifier

How to diagnose and fix it

  1. Connect a scan tool and record all stored codes in every module, then clear codes and verify whether U0337 returns immediately
  2. Check battery voltage and charging system output to rule out low-voltage conditions that can corrupt module communication
  3. Inspect the CAN bus wiring and connectors at the battery charger control module for corrosion, damage, or loose pins
  4. Verify the battery charger control module part number and software calibration against the manufacturer's latest available version
  5. Reprogram or update the battery charger control module and any related modules with the latest OEM software
  6. If programming fails or the mismatch persists, perform a module configuration or initialization procedure per service information
  7. Replace the battery charger control module only after software and wiring checks confirm an internal fault

Why software mismatch beats hardware failure here

  • This code almost always points to a software or configuration mismatch rather than a failed battery charger control module, so replacing the module first is a costly misdiagnosis.
  • A weak or failing 12-volt battery can cause modules to drop off the network during programming, leaving incompatible software flags that mimic a genuine module fault.
  • Aftermarket battery charger control modules or unauthorized software updates are a common hidden cause because their firmware identifiers do not match what other modules expect.
  • U0337 can be stored alongside U-codes for other modules, and clearing only the battery charger code without addressing the root network or programming issue will usually bring it back.
  • Some vehicles require a specific initialization or learn procedure after battery charger module replacement, and skipping it sets an incompatibility code even with correct hardware.

Can I keep driving with U0337?

The vehicle is generally safe to drive because the fault is a software incompatibility rather than an immediate safety system failure, but avoid long trips if the charging system warning is active and do not ignore repeated battery drain or charging faults. Have the software mismatch corrected promptly to prevent secondary electrical issues.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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