I bought NX 300h in July 2016. Everything worked well luntil November when I first noticed an alert from blind spot monitoring (BSM) that it was malfunctioned. First I thought there was a frost on the sensor so I turned the engine off and it went away. Unfortunately, this malfunction alert have kept happening like every 3-4 weeks. I took my car to my local Lexus dealership last week. They said they saw a scruff on a side mirror and thought something hit it to cause the sensor to go off. TBH, I can barely see any scruff or scratch on the underside of the window. They reset the program and handed it back to me. Now three days later I got another two alert of the same BSM problem again. My car is new and has never been in an accident or modificaiton, or got hit by anything.

Has anyone every experience similar problem like mine? I will bring it back to the dealership again. It's really annoying.

I have never seen that on any of my Lexus cars with BSM, including our NX. Good luck with your dealer. It would be frustrating if they keep struggling to get it resolved.

I guess I'm confused --- the BSM sensors are on the bumpers, and they trigger the light on the mirrors to come on, so how would a scuff on the mirror cause a malfunction of the BSM?

Best,
dCota

Agreed. The sensors are behind the rear bumper on the sides. If the dealership said a scratch on the mirror is what's causing it, then... Well that's scary.