Check engine light comes on but car runs great 2002 bmw 325i and

The check engine light could be any number of things and the only way to find out is have the codes scanned. The brake light issue is common on E46 3 series. It is an issue were the brown ground wire that goes into the lamp housing melts at the connector causing a loose ground connection. The connector needs to be replaced and also add additional grounding wires to prevent further issues. And for fuel additives either use the cheveron techron, or the bmw fuel additive(the bmw stuff is the exact same thing, so just use which ever is cheaper).

hi
the engine light flashing means your vehicle needs serving i.e oil change, filters, etc.


hope this helps
Kind Regards
RAHUL_hunk

i just replaced the radiator and now the check engine light is coming on 95 BMW 325. I?s there a correlation