Steering Assist Control Unit Error

Polo 9N, manufactured in 2006, engine code AXR.

We are experiencing a power steering failure with the following error message:

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Address 09: Central Electronics
Label file: RKS\6Qx-937-049-C.lbl
Part number: 6Q1 937 049 D
Component: 00BP BN-SG. 1S34
Encoding: 09646
Operating number: WSC 31414
VCID: 3C73468D2C30C9FE87F-5102

"One error found:"
01309 - Steering assist control unit (J500)
49-00 - No communication.
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Can someone tell me where I can find this control unit?
Thank you.
Best regards, Klaus.

I'm afraid there's a problem with the hydraulic pump .

Right now, the steering is working again (at least when the car is stationary), and the warning light is off.
Can VCDS be helpful in addressing this issue? Are there any relevant diagnostic trouble codes (DTCs)?

Best regards, Klaus.
EDIT: Thanks for the graphic, I hadn't seen it before.

Check the cable in the area of the left bracket near the splash guard at the lowest point. Cut open the black sheathing there and carefully inspect the two twisted CAN cables and the remaining insulation of the cables. If these are swollen due to constant moisture, the copper will be oxidized. In such cases, the problem is often a lack of communication with the steering assist control unit or a voltage that is too low in the memory.

Sometimes, the Linkhilfe control unit is malfunctioning.