What it means
Input power line B voltage above expected range. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
The module monitors its B input-power feed for voltage above the allowed range. This code sets when the B-feed voltage is too high, which can disturb the module’s operation and communication with other systems.
Common causes
Most likely first.
- Alternator regulator failed
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
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
- Record freeze-frame data and scan all modules for high-voltage or communication codes to determine whether overvoltage affects the whole vehicle.
- Check battery condition and charging-system output, focusing on whether the alternator regulator is allowing excessive voltage.
- Inspect the module’s B-feed connector, wiring, fuse, and ground for heat damage, poor contact, or incorrect repairs.
- Measure B-feed voltage at the module and compare it with the manufacturer's specification, including when the fault is active.
- If charging and B-feed voltage are within specification, inspect gateway routing and CAN network integrity and termination using the vehicle wiring diagram.
Common fixes
- Secure or clean a poor B-feed connection or ground.
- Repair damaged B-feed wiring or replace a faulty connector terminal.
- Repair or replace a confirmed faulty alternator regulator.
- Repair the gateway or CAN network fault if the B feed is correct.
Can I keep driving?
If multiple systems warn, shut down, or enter limp mode, stop driving safely; continued overvoltage can damage modules and disable vehicle functions. With no symptoms, limit driving to a short trip for diagnosis and stop if electrical or drivability problems develop.
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.