What it means
The vehicle bus reports loss of communication with active grille shutter module D. 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 D controls its assigned movable flaps in the front grille, adjusting airflow through the radiator area and aerodynamic drag. This code sets when the vehicle network stops receiving expected messages from module D, so its status and control cannot be confirmed.
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 and voltage codes, and use freeze-frame data to determine whether the fault is isolated to module D.
- Check whether active grille shutter module D communicates with the scan tool and reports shutter status.
- Inspect module D's connector and harness for loose pins, corrosion, moisture, impact damage, or chafing.
- Test module D's power and ground connections under the manufacturer's specified conditions.
- With the vehicle powered down as specified by the manufacturer, check the network branch to module D for opens, shorts, or poor connections.
- If power, ground, and network wiring are correct but module D stays offline, confirm module failure using the manufacturer's procedure.
Common fixes
- Secure a loose connector at active grille shutter module D.
- Repair damaged or corroded module D wiring or network connections.
- Restore module D's power or ground supply.
- Replace module D if its circuits are sound and it remains unable to communicate.
Can I keep driving?
If engine temperature remains normal and no cooling warning appears, a short cautious trip may be possible; monitor the temperature and avoid heavy loads in hot weather. Stop if temperature rises, since the grille flaps controlled by module D may not move as required.
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.