Fault codes

[Ricochet]

Hi I have a 2004 x3 3.0 l petrol I have engine light on and diagnostic says running lean bank 1 and bank 2 I have replaced all o2 sensors and then reset fault codes light goes out for about 70 miles then same fault ones back any ideas on what's wrong many thanks Ray

[Greydog]

Hi Ray

Welcome to the Forum

What appears as a fault with the O2 sensors can often be caused by other things, have you checked the inlet side for vacuum leaks.The fact it takes around 70 miles would make me suspect a leak somewhere as if a sensor is wrong or dead the fault would be instant.

What diagnostic did you use was it BMW specific or a Generic one?

Good Luck 

Dave

[Ricochet]

It's a bmw scan tool with live data I did wonder if there was a vacuum leak somewhere it does have a small oil leak nothing major so will check inlet manifold and hoses suppose I was hoping it was sensor thanks for advice  Dave