What it means
A control module has detected that the software in hybrid/EV battery interface control module B is incompatible with its own software or configuration. Battery-system functions may be affected; the specific effects depend on the vehicle.
How it works
Hybrid/EV Battery Interface Control Module B manages a designated interface in the high-voltage battery system, separate from interface module A where the vehicle uses multiple modules. U033B is set when another controller finds module B's software or configuration incompatible with its expectations, potentially affecting the battery functions assigned specifically to B.
Common causes
Most likely first.
- Incorrect or incompatible battery interface control module software
- Module replacement without required programming or configuration
- Incorrect module part number
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Save freeze-frame data and scan all modules for battery and communication codes, noting whether reports identify interface module B or other battery modules.
- Check whether the fault followed battery-system service or module replacement, and verify that battery interface control module B has the correct part number.
- Use a capable scan tool to read module B's software and configuration identifiers and compare them with manufacturer data for the vehicle.
- Inspect accessible low-voltage wiring and connectors for module B for looseness, corrosion, or damage without opening the high-voltage battery.
- If the module and connections are correct, have module B's configuration and software compatibility checked and programmed as required, then rescan.
Common fixes
- Reconnect or repair an accessible low-voltage connection to interface module B.
- Replace module B with the correct application if its part number is wrong.
- Program or configure battery interface control module B to match the vehicle.
- Apply a manufacturer-approved update to the related modules if needed to resolve software compatibility.
Can I keep driving?
Do not ignore a hybrid or high-voltage battery warning, reduced power, or unexpected shutdown; stop safely and arrange assistance if any occurs. A mismatch affecting interface module B can lead to restricted battery operation or loss of vehicle functions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.