Pittys sti

Hi. Just got my car back from a Subaru specialist in Hannam Bristol followning a cambelt and brake pad change. Whilst there I asked them to put it through a diagnostic health check on their computer.

Three codes came up:
1- Air flow meter (MAF)
2-cam sensor and
3- another cam sensor

I suspected the MAF to be faulty as the cars fuel use is terrible (around 13mpg!) and will be replacing it tomorrow. But what are cam sensors and what do they do? If I don't replace them soon am I likely to do any serious damage? Also can anyone recommend somewhere I can get them cheaper than subaru main dealer?

One last thing, whilst driving home white smoke came pluming from under my bonnet and smelt awfull. I can't see any obvious leaks, but under the car an oily residue is dripping from somewhere. It looks to clean to be oil but is greasy. I will be phoning the garage tomorrow too see what they've done to cause this and how they're going to resolve it. I'll keep you posted as to there service.