...just behind the coolant expansion tank. From inside to outside, they are fuel pump/oxygen sensor heater relay, main relay, and evaporative purge valve relay. If the main and fuel pump relays haven`t been changed, it`s a good idea to just replace them. A failure of either one will strand you. John 88 ///M3 Cinnabar
Where are the relays located on the E30 M3? Also, How do I check if there are all working properly?