What it means
The vehicle bus reports loss of communication with active aerodynamic feature module B. Powered spoilers, air-dams or wheel-arch closures controlled by this node default to a fixed position.
How it works
Active aerodynamic feature control module B operates a powered aerodynamic device assigned to that node, such as a spoiler, air dam or wheel-arch closure. Other modules expect it to send status messages over the vehicle network; this code sets when those messages stop arriving for the required time.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
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 all modules for communication codes and freeze-frame details to see whether module B alone dropped offline or several modules lost network messages together.
- Check whether the module B aerodynamic feature is stuck or inoperative, and inspect its connector and nearby harness for looseness, water, corrosion or damage.
- Using the wiring diagram, check that module B has the specified power and ground, since a supply fault can make it disappear from the network.
- Inspect and test the network wiring to module B for opens, shorts or poor connections, following the manufacturer's procedures.
- If power, ground and network wiring are sound, confirm the fault is current and assess module B for failure using manufacturer diagnostic procedures.
Common fixes
- Reconnect or repair a loose, corroded or water-damaged module B connector.
- Repair an open or short in the network wiring serving module B.
- Restore the module's specified power or ground by repairing its feed, fuse or ground connection as indicated by testing.
- Replace module B only after its power, ground and network connections test correctly.
Can I keep driving?
If the vehicle drives and steers normally, a short trip may be possible, but the module B spoiler, air dam or other feature may remain in a fixed position and reduce aerodynamic performance. Avoid high-speed driving if the feature is visibly loose or obstructing airflow, and stop if other warnings affect vehicle control.
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.