Audi Side Assist + S3 Mirror Shells

My biggest retrofit so far. It took me almost a year to collect the parts. I was installing first generation of the system (native for my car). 2nd generation uses new Bosch radars with new cross traffic monitoring, but they need some extra adapters to fasten them to the old bumper.


5Q0 907 566 A – master radar
5Q0 907 568 A – slave radar

I bought them used from the same car, no calibration was required.

Mirror indicators:

8V1 949 145 – left side
8V1 949 146 – right side

OR you can buy counterparts from an alternative Polcar manufacturer, 3X cheaper:

13C1198E – left side
13C1208E – right side

Genuine S3 mirror shells with indicator sockets cost ~€300; part numbers are 8V0 857 527 C 3Q7 and 8V0 857 528 C 3Q7. Part numbers of primed shells ready for the paint are 8V0 857 527 E and 8V0 857 528 E.

I bought cheap replicas from AliExpress. Many people install them just for the aesthetics but I needed them because of the sockets. The plastic of the shells is a little thinner than the genuine ones, and indicators protrude above the surface. I had to cut latches with a knife to fit them firmly. On the inside, I added a few drops from a glue gun for reliability.

The wiring kit came from AE as well. The seller sent me the kit for GEN2 facelift cars with new 8-pin connectors 4F0 972 708, so I had to replace them with old 4E0 972 713 12-pin connectors.


You need to disassemble half of the interior and drop off the rear bumper: remove all plastic panels on the left side, remove front door cards, wire the cable under the dashboard from the left side to the right, dismount the mirrors themselves. So I found a retrofit / electrical specialist to do the work. It took him two days in total.

Wiring diagram:

There is its own CAN bus between the radars in the bumper. From the master module (right) CAN Comfort goes to the Gateway. From the slave module (left) – to the fuse box and, passing under the dashboard, to the door rubber connectors. And there is one more connection inside the door on the way to the mirrors.

Unlike all VW cars, on the Audi A3, the radars are fastened directly to the bumper, it has mounts inside.


19 Gateway – add 3С Lane Assist to the list
3С Lane Assist – long coding is 030211

Enable in 17 Instruments Cluster:

Byte 5 Bit 3 - Lane Change Assist installed

Enable in 5F Infotainment System:

IDE04300-ENG117511-Vehicle menu operation-menu_display_side_assistant, activated
IDE04300-ENG117515-Vehicle menu operation-menu_display_side_assistant_after_disclaimer, activated
IDE04307-ENG117742-Vehicle function list BAP-SWA_0x1A, activated
IDE04307-ENG117743-Vehicle function list BAP-SWA_0x1A_msg_bus, Databus extended

This will add new item in “Car Assistants” menu with the knob to control the brightness.

In use

Radar beams have around 20 meters in length. The system stops working below 35km/h, so it is useless in the city downtown and traffic jams. Sometimes they also react to the car behind you in the same lane. Vespas are not recognized at all, but motorcycles are OK.

Official video:

To be continued…

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