Hi, I'm new to the forum and was wondering if anyone can help me understand this problem. Intermittantly a warning comes onto my idrive stating engine fault reduced power (I don't loose any power), my brother in law took it into a garage and they said it would need a new battery negative lead, Could this be right...........

 

Is it a 535? Year and model of your car would help.

 

Hi it's a 530d 2004

 

I would suggest reading the codes to see exactly what goes wrong

 

do a search for "engine malfunction" in the forum and you will get plenty of results

 

Check your battery cable to make sure it's tight,,, check your battery to make sure it's good and third get your alternator tested. Post a pic of message