DTC U0284, Additional Diagnostics Added – 2017-2019 Subaru Impreza

NHTSA ID Number: 10150933

Manufacturer Communication Number: 07-140-18


This bulletin announces an additional troubleshooting step to follow when diagnosing a DTC U0284: “LOST COMMUNICATIONWITH ACTIVE GRILLE SHUTTER MODULE “A”. Water intrusion into the harness wiring leading to connector B63 for the Active Grille Shutter (AGS) may lead to corrosion of the harness wiring and/or connector terminals and result in a communication loss with the ECM.


3 Affected Products





This bulletin announces an additional troubleshooting step to follow when diagnosing a DTC U0284: “LOST COMMUNICATIONWITH ACTIVE GRILLE SHUTTER MODULE “A”. Water intrusion into the harness wiring leading to connector B63 for the Active Grille Shutter (AGS) may lead to corrosion of the harness wiring and / or connector terminals and result in a communication loss with the ECM.



The installation method of the corrugated plastic harness protection tube was changed to prevent damage starting with the following VINs:

  • 4-door: J3624930
  • Wagon: J3751997



REMINDER:  Customer satisfaction and retention starts with performing quality repairs.

Always refer to the applicable Service Manual and review the full requirements of the repair being performed.  The Service Manual procedures contain information critical to performing an effective repair the first time and every time.  This includes but is not limited to: important SAFETY precautions, proper inspection criteria, necessary special tools, required processes and related onetime-use parts needed for a complete and lasting repair.

The AGS harness connector B63 is located at the end of the AGS assembly in the l/front as shown below.


IMPORTANT:  Before proceeding with any other electrical testing as directed by the current Service Manual diagnostics, access and disconnect the AGS harness connector.  The photos below show both sides of the harness connection with corrosion present.  If corrosion or an open circuit in the wiring is identified, replace both the bulkhead wiring harness and AGS assembly following the procedure outlined in the applicable Service Manual.

NOTE:  Do not attempt to repair the wiring or clean the connector terminals.  If there is no corrosion in either connector, check the wiring to the harness connector and confirm there is not an open circuit, broken wire as shown below or unexpected high resistance to indicate corrosion in the wiring.  If no wiring or connector damage is identified, proceed with electrical testing Steps 3 to 6 as outlined in the applicable Service Manual for DTC U0284.

The related Service Manuals will be updated with this new initial diagnostic step.

NUMBER: 07-140-18
DATE: 10/09/18



Download (PDF, 606KB)

NUMBER: 07-140-18
DATE: 10/09/18



Download (PDF, 606KB)


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Last update on 2020-04-08 / Affiliate links / Images from Amazon Product Advertising API

Last update on 2020-04-08 / Affiliate links / Images from Amazon Product Advertising API

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