What it means
A receiving control module has detected invalid data from Electronic Brake Booster Control Module A. The code does not specify which data is invalid or what effect it has on braking.
How it works
Electronic Brake Booster Control Module A reports brake-booster status and related data to other modules. U055F means a receiving module considers data from this particular brake booster module invalid; it does not confirm that braking assistance has failed.
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 the brake, chassis, and body modules and save freeze-frame data and related codes before clearing anything.
- Check for brake, booster, or stability warnings and note any change in pedal effort or braking behavior.
- Inspect Module A's connectors and accessible wiring for damage, corrosion, loose terminals, or signs of water intrusion.
- Verify the module's power, ground, and network circuit using the wiring information and manufacturer's specification.
- Check for gateway communication or software/configuration mismatch, especially after brake-system or module service.
- If the circuits and configuration are correct, follow vehicle-specific diagnostics to assess the booster module and its reported inputs.
Common fixes
- Reconnect or repair a loose or corroded Electronic Brake Booster Control Module A connector.
- Repair damaged wiring or correct a poor module power or ground connection.
- Correct a gateway routing or module configuration problem.
- Apply the correct software or programming if a mismatch is confirmed.
- Repair or replace Module A only after vehicle-specific tests confirm an internal or input fault.
Can I keep driving?
Because this code involves brake-booster data, treat a hard pedal, reduced assist, brake warning, or changed stopping behavior as urgent and avoid driving; arrange inspection or towing. If braking feels normal, drive only as needed and cautiously, since loss of assist can increase pedal effort and stopping distance.
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.