MKD

Hey guys,

Yesterday I got the "Active Blind Spot Assist Inoperable", alongside "Lane Assist Inoperable" errors on the dash.

However, the cruise control (Distronic) still works fine, and I did notice the Park Assist arrow show up, so that should be working too.

I ran it on my Foxwell scanner, and under the SGR-Radar sensor control unit, I got the following fault codes:

B1A9F97 - Stored&Current(Event) - The event memory has a malfunction. The system function is restricted.
B175515 - Stored&Current - The output for the ambient lamp has a malfunction. There is a short circuit to positive or an open circuit.
C375200 - Stored&Current - Check component B29/7 (Right rear bumper radar sensor)

Looks like the first 2 errors cleared, however the C375200 remained.

I got under the car, and popped out the right sensor. No visible damage, buldges or even dirt - just a bit dusty.

I did the same with the left sensor, and same thing - clean and no visible issues.

I did notice the part numbers are the same - so I tried to interchange them, and see if the fault follows.

Strangely, the same error remains, indicating the rear right radar sensor.

I figured it might be coding related, but reading up about it, the advice is that if all numbers match, no coding required, as in this instance.

I also unplugged it and ran another scan, which gave a CAN bus communication error, indicating the wiring is okay and reading when plugged.

So now I'm stumped - I don't know what to look for next.

Any ideas appreciated... Thanks in advance.

Tom in Austin

What a nuisance ... I saw "Active Blind Spot Assist Inoperable" messages intermittently around Christmas time last year but haven't had it since.

Robb92914

My car was at the dealer for 4 months for this and after software update, new sensor, and "coding" they ended up saying I needed a new bumper because the bracket that holds the new sensor the replaced was damaged somehow so it was loose.

as.thompson

Duct tape to solve the problem.

MKD

Just to update on the initial fault codes:

MODULE: KI-Instrument cluster
B1A9F97 - Stored&Current(Event) - The event memory has a malfunction. The system function is restricted.

MODULE: DMFL-Left front door
B175515 - Stored&Current - The output for the ambient lamp has a malfunction. There is a short circuit to positive or an open circuit.

So, should not be relevant to the radar sensor (I think the scanner just combined all the fault codes in the same module on the scanner screen).
The brackets were nice and clean, did not move around, sensors clipped in firm and proper, and no obstructions - so I can't imagine it's that..

Using my scanner, I can look at the live data, and the trouble radar sensor does seem to give readings within the specific range when moving near/further away from objects..

Really strange.. I have the feeling it's not the sensor itself, but something else tripping up the system.

VII

You are not mixing the ultrasonic and the blind spot radar sensors right?

MKD

What do you mean by mixing?

VII

Meaning the error is for radar but you are running diagnostics on ultrasonic.

MKD

Today I drove it, and strangely the fault did not come up on dash.

I ran the scanner again, and the fault was just stored (no longer current) and cleared fine.

However, driving it in traffic did not give the blind spot warnings like usual, so it still seems to not be working.

I entered the settings and the function is set to active. Turned off and on but still no return of function.. So strange.

I ran a full system diagnosis and seperately for the radar control unit getting the same fault.