Is there a usual culprit for this light coming on or must the car go to the dealer straight away?

 

I suggest going to the Dealer. It will mean that an error message has been recorded on the computer. This could be many things, but get it down to the dealer to plug it in and find out.
Better safe than sorry.

 

Mine comes on every now and then MY00 induction kit and exhaust.

 

I was going past Glenshee when my light came on , called the dealer and they said it would have been the oxygen sensor because of the temperature/alltitude. Light hasn't been on since.

RB5 162

 

Mine came on in my last car when I was going down the motorway having just come from the dealer. He said it was just a bit of dirt in the petrol (I had just filled up).

If in doubt he said, 3/4 starts of the ignition and if it stays on then you should get it checked. Mine went while I was driving, plus I didn't want to stop on the motorway.

 

wrx it shouldn't do that.