Came on today. Never has before. '09 C30 T5. 104k
Car is running normally. Volvo just changed the oil last month. It's full, and color is fine.
I'm dropping it off for servicing next week. Leaving it for a week.

What are the most likely causes, and what should it cost?

 

Most common on that car is PCV breather box and leak detection pump. I don't know the costs off hand though.

 

Thanks. You were helpful with my sunroof leak, as well.
I also need new front brake work. Any advice on that?
Les Schwaub is in town, while Volvo is two hours away. Quality and cost similar?

 

check engine is not about oil

its most likely something to do with the emissions system. Have the code read, can be done free in many parts stores.

 

Yes, it was the gas cap. I should know of such possibilities by now.
But the dealer found a couple of other issues that needed attention, so it worked out fine.
Thanks