My car won't start in normal way.
(which means I have to push & hold for 10-15 sec on ACC to get started...)

So I dropped my car today, didn't think about NAVI bypass...

Service Consultant called and asked what is aftermarketish-looking button on the dash.
So i told him that is NAVI bypass button and had it for year without any problem.

He didn't say anything at that time... but will this void warranty?

 

It might void your navigation warranty but that's about it.

 

It probably won't void your warranty unless the dealership can prove that the Navi Bypass device caused the problem. This is what my dealership had told me. Not every dealership will treat you the same though...