Engine warning light from oxygen sensor

[Rachael D]

I have a BMW 1.6 sport 2012 and on day of passing mot with no advisory’s the engine light later came on been back and forth to garage who diagnosed oxygen sensor this was replaced and light always comes back on the 2nd time I drive the car- the ECU was sent off for diagnostics as they said it was a known fault with my make model etc they kept ECU for nearly 2 weeks and returned it with “no faults” so all 3 components checked multiple times sensor ECU and wiring - the light is back on and all garage is saying now is go to BMW any ideas welcomed gratefully as can’t afford to go to BMW atm car drives fine 

[Greydog]

Morning Rachael

O2 sensors measure the ratio of air to unburnt fuel in the exhaust before and after the Cat so the engine management can make adjustments, so you have 2. An air or vacuum leak can trigger the EML (engine management light) as can EGR issues 

If I were you I would Google the Register of BMW Specialists and find one near you as they will (a) have the equipment to diagnose your cars issues properly (b) they are not going to be any more expensive than the Garage you just used.

I hope this helps

Dave