What it means
Intermittent dropouts or noise on input power line B. 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
How it works
The module monitors its B input-power feed for dropouts and unstable voltage. This code sets when the B supply becomes intermittent or erratic, potentially causing the module to stop communicating or operate inconsistently.
Common causes
Most likely first.
- Connector loose or corroded
- 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
- Save freeze-frame data and scan all modules for matching communication or voltage faults to see when the B-feed interruption occurred.
- Inspect the module’s B-feed connector, fuse, wiring, and ground for looseness, corrosion, chafing, or heat damage.
- Monitor voltage at the B feed while gently moving the accessible connector and harness to reveal intermittent contact.
- Check supply and ground voltage drop under the manufacturer's specified test conditions to find resistance that appears only under load.
- If B-feed voltage stays stable, use the vehicle wiring diagram to check gateway routing and CAN wiring and termination.
Common fixes
- Clean and secure the B-feed connector or ground.
- Repair broken, chafed, or high-resistance B-feed wiring.
- Replace a damaged fuse terminal or connector pin.
- Repair a confirmed gateway or CAN termination problem if the B supply is stable.
Can I keep driving?
If the module or a dependent safety or drivability function cuts out, stop safely and arrange diagnosis because the fault may become a full loss of operation. If only noncritical functions are affected, keep driving limited and avoid relying on functions that are intermittent.
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.