I changed the spark plugs on my mk3 2.0RX today, and forgot to plug the MAF plug in before starting the car. I now have the EML and vehicle dynamics lights on and the cruise control light flashing intermittently - having looked on Youtube this seems to be a standard warning light sequence. Is there any way of cancelling the lights without using a code reader. If not where is the OBD port located?

OBD is normally under the steering wheel on Subarus.  On older cars there is a short sequence to clear the codes that involves connecting a pair of plugs in the footwell then driving at 11mph for 100 yards, or something similar, but I've never needed to do it on a modern Impreza so I have no idea if the same will work with your car.  I would imagine it is possible without special equipment or having to disconnect the battery for an hour or two.

Thanks Adam. From what you said, is it possible that disconnecting the battery for a couple of hours might clear them? The battery was disconnected for about an hour when I changed the nearside plugs. The lights came on when I started the car on (first) changing the offside plugs (to check everything was OK)!

On an older Impreza it would work, so I guess it must be worth a try!

It worked! Thanks again.