What it means
The vehicle bus reports loss of communication with active grille shutter module B. The aerodynamic flaps in front of the radiator stay in their default position, increasing drag and possibly affecting cooling.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
Active grille shutter module B controls its assigned set of movable front grille flaps, which regulate airflow and aerodynamic drag. The vehicle network expects messages from module B; this code sets when those messages are absent long enough for another controller to declare a communication loss.
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 network and voltage codes and review freeze-frame data to determine whether the fault is isolated to module B.
- Check with a scan tool whether module B responds and whether its shutter status data can be read.
- Inspect module B's connector and harness for water, corrosion, loose pins, impact damage, or chafing.
- Test module B's power and ground connections under the manufacturer's specified conditions.
- With the vehicle safely powered down as specified, check the network branch to module B for opens, shorts, or poor connections.
- If module B has good power, ground, and network wiring but remains offline, confirm the diagnosis using the manufacturer's procedure before replacing it.
Common fixes
- Secure a loose connector at active grille shutter module B.
- Repair damaged or corroded module B wiring or network connections.
- Restore the module B power or ground supply.
- Replace module B if its circuits are sound and it still will not communicate.
Can I keep driving?
A short trip may be reasonable if engine temperature remains normal and no cooling warning appears, but monitor the temperature and avoid demanding driving in hot weather. Stop if the engine begins to overheat, because module B's grille flaps may not move as commanded.
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.