Which is bank 1
 

I have an O2 sensor error on Bank 1 Sensor 1. I know sensor 1 is pre cat but which bank is bank 1. As I sit in the drivers seat is it the left or right side of the engine?

Thanks all

Just replace them both. If one is dead the other is not too far behind.

Plus to answer the original question bank one is the drivers side.

Bank 1 is the Passenger Side... Bank 2 is the Driver Side.

Beware of confusion between LHD and RHD cars.

So what it comes down to... replace both!! Is this a hard DIY? I have all 4 to do actually..

It's not the case on every car that all 4 need doing (otherwise OBD would throw 4 codes). That said it can make sense to do all at same time to save future hassles but at £125 each per sensor from the dealer many would rather spend money elsewhere. If money no object I'd get dealer to do all work it in any case.

Afaik the Lambda O2 sensors on 4.4i are made by Bosch and readily available outside of dealer network cheaper.

From inside car :

Bank 1 is furthermost to YOUR right when sat in front seat of ANY market car.

Bank 2 is furthermost to YOUR left when sat in front seat of ANY market car



Ourtside & looking down into engine bay directly from centre front of car.

Bank 1 is to your left.

Bank 2 is to your right.


.....................I think LOL !

Sorry Guys... forgot about the right side drive cars. Looking into the engine bank two is on your right... Bank1 is on the left.

Do some research but http://cgi.ebay.co.uk/BMW-Front-Lamb...QQcmdZViewItem