The check engine light came on in my 1991 legacy turbo. Does anyone know where to get a cheap code reader or is there a way to get a USB plug and interface with a laptop computer?

Cheers!

91 is a obd-1
so there is no plugging in
you connect the plugs under the dash and watch for the blink code

read this
http://autorepair.about.com/library/ts/obd-i/bl-dtcs-09a.htm

My site has similar info
www.surrealmirage.com/subaru/engine.html

I'd also recommend
www.bbs.legacycentral.org