What it means
A receiving control module has detected invalid data from Special Purpose Vehicle Control Module B. The code does not specify which data is invalid or what functions the module controls.
How it works
Special purpose vehicle control module B sends data to other modules for functions defined by the vehicle maker or its special equipment. U055B is set when a receiving module rejects data attributed to module B as invalid; the code does not identify the data or function involved.
Common causes
Most likely first.
- Module internal fault or sensor input drift
- Software version mismatch after replacement
- Gateway module routing CAN messages incorrectly
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
- Scan all modules and save freeze-frame and communication details to identify the receiving module and any related special-equipment or network faults.
- Determine which vehicle functions depend on special purpose vehicle control module B by checking the equipment information and noting any affected functions.
- Inspect module B's connectors, grounds and harness for looseness, corrosion, moisture or damage, including wiring added for special equipment.
- Use a capable scan tool to review available module B data while operating the affected equipment or functions.
- Check other modules for gateway or communication faults that could indicate incorrect routing of module B's messages.
- If wiring and routing are sound, investigate a module fault or software/configuration mismatch, particularly after a module or equipment change.
Common fixes
- Repair damaged or corroded wiring and connectors at module B.
- Correct poor power or ground connections to module B.
- Restore the correct software or vehicle configuration after a module or equipment change.
- Repair or replace module B if it continues sending invalid data.
- Correct gateway routing if related network faults show that its messages are being misdirected.
Can I keep driving?
Driving guidance depends on which special-purpose functions module B controls; confirm that affected equipment and any safety-related functions work before driving. If an essential vehicle or equipment function is unreliable, do not use the vehicle until it has been assessed.
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.