I do work in automotive EMC testing and it's nearly always the voltage conversion at fault when you fail tests or influence other devices. Buck-Boost converter

I do work in automotive EMC testing and it's nearly always the voltage conversion at fault when you fail tests or influence other devices. Buck-Boost converters are a noisy and finicky thing, and not easy to debug if you use a monolithic IC from the cheapest vendor. Quite annoying discussions.