BMW 330 emission system warning light

[PistonReg]

The yellow warning light's come on on my E46 330. I believe it monitors various things, but before I head off to BMW for their expensive plug in, is there a known common cause for this on the car?

[Neil_Sc]

Could be one of many things, do you have any symptoms?

[HarryW]

Oil level

[PistonReg]

Neil_Sc said:

Could be one of many things, do you have any symptoms?

No symptoms at all - car runs well. She does use about a litre of oil every 1500/2000 miles, but always has done.

I had the light come on about 8 months ago after an hour in heavy M25 traffic, but it went off about 100 miles later and has now been on for 2 days.