What it means
The plus line of bus B is shorted to battery voltage. The bus stops carrying valid frames. 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
Bus B uses a plus line to carry CAN communication between connected vehicle modules. The control module monitors that line, and this code sets when the bus B plus line is high, typically because it is shorted to battery voltage and valid messages stop.
Common causes
Most likely first.
- Bus-B plus shorted to battery
- 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 all codes and freeze-frame data, then check which bus B modules have no response and whether related bus B or gateway faults are present.
- With the circuit safely powered down as directed by the manufacturer, inspect the bus B plus wire and nearby harness for chafing, crushed insulation, or contact with a battery feed.
- Check connectors and the gateway for bent pins, corrosion, or evidence that the bus B plus line is bridged to another circuit.
- Test the bus B plus line for a short to battery voltage and check bus operation and termination against the manufacturer's specification.
- If the wiring passes, isolate modules and check gateway routing using the manufacturer's procedure to find a device internally pulling the bus B plus line high.
Common fixes
- Repair chafed or damaged bus B plus wiring that is shorted to a battery feed.
- Separate and secure wiring that is contacting another powered circuit.
- Repair corroded or damaged connectors on the bus B plus circuit.
- Repair or replace the gateway if testing confirms it is routing or driving bus B incorrectly.
- Replace a module only if testing confirms it is pulling the bus B plus line high.
Can I keep driving?
Avoid driving if loss of bus B communication disables safety or essential functions, and expect warning lights or reduced operation in affected systems. If those functions remain normal, limit driving until repaired because modules that depend on bus B data may shut down or enter limp mode.
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.