Hi everyone,

I'm experiencing an intermittent issue with my blind spot monitoring (BSM) sensors and hoping someone here has seen something similar.

The system has been working fine overall, but every now and then it becomes unavailable — a warning message pops up saying the sensor is no longer accessible. The behaviour is very inconsistent:

- Sometimes the sensors work perfectly after shutting the car off for the evening, but are gone the next morning on startup.

- There are days when everything works flawlessly — I can manually enable/disable the system without any issues — and then other days when it simply doesn't work at all.

- Weather doesn't seem to be a factor. The problem occurs whether the car is freshly washed or hasn't been near water for days.

My suspicion is that there may be a wiring issue somewhere — perhaps moisture getting into a connector or some intermittent contact — but visually everything looks fine. The connectors appear dry and clean, and when I physically unplugged one of the sensors, the car correctly detected it as disconnected, which suggests the detection logic is working.

I plugged in an OBD scanner and it did throw a calibration-related fault code. However, I'm not sure whether that's the root cause or just a side effect of the dropout. Interestingly, after reading the fault with the scanner, I restarted the car and the problem disappeared — only to return again after driving for a short while.

I'll attach some photos and the fault code screenshots below.

Has anyone dealt with something like this? Could it be the sensors themselves, the wiring harness, or is a calibration procedure actually needed here? Any advice on where to start would be really appreciated!

How old ist the Battery?

at the end of sixth year with my previous 2016. Mk3

i had to replace one of six rear parking sensor and wires to all sensors - dealer charged 163e

result of salted(winter season) roads in Latvia

15 hours ago, MartiniB said:

at the end of sixth year with my previous 2016. Mk3

i had to replace one of six rear parking sensor and wires to all sensors - dealer charged 163e

result of salted(winter season) roads in Latvia

The parking sensors are working fine no problems there, at first, I thought they might be the issue, but now it looks like the problem is with the blind spot system.

As for salt, I agree — that’s why I cleaned all the connections, but problem still actual with blindspot.

16 hours ago, Cairus said:

How old ist the Battery?

It’s not new replaced it ~ December 2024.

Charge Battery