What it means
A fault is detected on the negative conductor of vehicle communication bus F; the code descriptor specifies a high condition. Which functions are affected depends on the vehicle’s network design.
How it works
Bus F carries messages between its connected modules over positive and negative conductors. This code indicates that the bus F negative conductor is at an abnormally high electrical level, which can make communication unreliable or stop it.
Common causes
Most likely first.
- Short to voltage or damaged bus F negative wire
- Loose or corroded connector
- A module or gateway fault
Symptoms
- Communication faults in modules using bus F
- Warning lights or messages
- Functions relying on bus F may be unavailable
How to diagnose it
- Scan all modules for bus F communication codes and save freeze-frame data to establish when the high condition occurs and which modules are affected.
- Consult the vehicle network diagram to trace the bus F negative conductor and identify its module and gateway connections.
- Inspect the negative wire and connectors for contact with a power feed, damaged insulation, corrosion, or displaced terminals.
- With the network isolated according to the manufacturer's procedure, test the negative conductor for a short to voltage and inspect the harness between connections.
- If the wiring passes inspection, use the manufacturer's isolation procedure to check whether a gateway or module is driving the negative line high.
Common fixes
- Secure or clean a loose or corroded bus F connector.
- Repair damaged insulation or a short from the negative conductor to a power source.
- Repair a damaged bus F negative wire or terminal.
- Repair or replace a confirmed module or gateway causing the high condition.
Can I keep driving?
A short trip may be possible if the vehicle behaves normally and only noncritical functions use bus F, but the network may lose communication. Stop driving if essential steering, braking, or powertrain functions are affected.
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.