OBD-II trouble code
U0337: Software Incompatibility With Battery Charger Control Module A
On a plug-in hybrid or electric vehicle, a module has detected that battery charger control module A — the onboard charger that converts AC power from a wall outlet or charging station into DC power for the high-voltage battery — 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 charger 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
- $150 – $650
- DIY difficulty
- Shop recommended
What does U0337 mean?
U0337 sets on plug-in hybrid and electric vehicles when a module on the network determines that battery charger control module A — the onboard charger (OBC) that manages AC-to-DC conversion when the vehicle is plugged in — is running a software or calibration version that is incompatible with the version-matched set the rest of the vehicle expects. The 'A' designation identifies this as the primary charger module on vehicles that use one, or the first of possibly two charger modules on vehicles with dual-charger setups for faster AC charging. The charger module works closely with the battery control module and pack sensor module to negotiate charge rate, monitor voltage and temperature limits, and safely stop charging when the pack is full or a fault is detected. Because charging involves managing significant electrical current safely, manufacturers release the charger module's firmware as a tightly version-matched set alongside the battery control system. When the charger module's software doesn't fit that set, U0337 is stored.
The cause is almost always service-related and centered on battery charger control module A. It was replaced and not programmed with the correct VIN-specific software, a battery system software update was applied to other modules but not the charger, a reflash was interrupted or used the wrong calibration file, or a used/reconditioned charger module was installed without being matched to this vehicle's battery pack and software set. Because the root cause is data rather than a failed charging cable, connector, or contactor, chasing it electrically leads nowhere — the fix is reprogramming the charger module to a matching, manufacturer-approved software set.
Because battery charger control module A directly manages how power flows into the high-voltage battery, a software mismatch is treated with caution — most vehicles will refuse to charge, charge at a reduced rate, or stop charging partway through rather than proceed on unverified charging logic, which is why this is rated medium severity. The vehicle should still drive normally on its remaining charge, but the plug-in charging function itself may be degraded or unavailable until the module is reprogrammed. On a plug-in hybrid, this typically means falling back to gasoline-only operation; on a full EV, it can meaningfully limit usable range until resolved.
Common causes
- Battery charger control module A replaced without correct VIN-specific programming
- A used or reconditioned charger module installed without being re-matched to this vehicle's battery pack and software
- Battery control module or pack sensor software updated but the charger module's calibration left out of step
- An interrupted or incomplete charger module reflash
- Reprogramming done with the wrong calibration file or charger hardware variant (e.g. wrong charge-rate configuration)
- Mismatched hardware/software part numbers after onboard charger service
Symptoms
- Warning light and a stored U0337 (often alongside other hybrid/EV battery-related codes)
- Vehicle refusing to begin charging when plugged in, or charging stopping shortly after starting
- Charging at a noticeably reduced rate compared to normal
- Charge-related error messages on the dash or infotainment display
- Vehicle driving normally on remaining battery charge or in gas-engine mode (plug-in hybrids)
- Condition typically appears right after charger module service, replacement, or a software update
Diagnostic steps
- 1.Confirm the recent history — U0337 almost always follows onboard charger service, a module replacement, or a battery-system software update; identify what was serviced.
- 2.Using a scan tool rated for hybrid/EV high-voltage systems, read battery charger control module A's software/calibration part number and compare against the manufacturer's current approved set for the VIN.
- 3.Note any companion codes from the battery control module or pack sensor module that help confirm the charger module is the mismatched unit.
- 4.Verify the module was programmed with correct VIN-specific software matching this vehicle's charger hardware and rate configuration.
- 5.Follow all high-voltage safety procedures before any physical inspection of the charging system.
- 6.Reprogram/reflash battery charger control module A to the matching, up-to-date calibration using a manufacturer-approved tool.
- 7.Clear the codes and confirm U0337 does not return and that plugging in initiates and completes a normal charge cycle.
Repair cost
$150 – $650
This is primarily a programming fix. Reprogramming the charger module typically runs $150-$400, and up to $650 when dealer-only high-voltage calibrations or specialized charging-system tooling are involved. If the charger module itself is faulty (rather than just mis-programmed) and needs replacement, that hardware cost is separate and typically higher on EVs and PHEVs; U0337 itself is usually resolved by correct reprogramming.
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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.