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U0285 — Lost Communication Active Grille Air Shutter Module B

Generic OBD-II · all makesNetwork / communication

Code U0285 indicates that the vehicle's main control module has lost communication with the Active Grille Air Shutter (AGS) Module B. This typically means the module is not responding to network requests or is not receiving power.

Symptoms

What causes it — most likely first

1. Failed Air Shutter Module B

Internal electronic failure within the module preventing it from communicating on the vehicle network.

2. Damaged Wiring Harness

Physical damage to the communication wires, often caused by road debris, corrosion, or rodent interference.

3. Loss of Power or Ground

A blown fuse or corroded ground connection preventing the module from powering on.

4. Corroded Connectors

Moisture intrusion at the module connector leading to poor electrical contact.

5. Network Bus Fault

A short or open circuit in the CAN bus wiring affecting multiple modules.

6. PCM/ECM Failure

Internal failure of the engine control module's communication circuit.

How it's diagnosed

  1. Perform a visual inspection of the grille area for physical damage to the shutters and wiring.
  2. Check all fuses associated with the active grille shutter system for continuity.
  3. Inspect the module B electrical connector for corrosion, bent pins, or loose connections.
  4. Verify 12V power and chassis ground at the module connector using a digital multimeter.
  5. Test the CAN bus communication lines for proper resistance and voltage levels.
  6. Use a bidirectional scan tool to attempt to ping the module and check for specific sub-codes.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make
Related codesU0284 — Lost Communication Active Grille Air SU0286 — Lost Communication Radiator Anti TampeU0287 — Lost Communication Transmission Fluid U0288 — Lost Communication Dcac Converter ContU0289 — Lost Communication Dcac Converter Cont

Frequently asked

Does this code mean the shutters are physically stuck?

Not necessarily. This is a communication code, meaning the computer cannot talk to the module; the shutters themselves may be functional or stuck, but the electronic link is broken.

Can I ignore this code?

While the vehicle remains drivable, ignoring it can lead to decreased fuel economy and may affect engine temperature regulation.

Should I replace the engine computer (PCM) to fix this?

No. It is extremely rare for U0285 to be caused by the PCM. The fault is almost always located in the shutter module, the wiring, or the power supply.