any ideas ? had a new key cut ages ago , never used it , until now i want to, forgot i had a new alarm ecu fitted not long ago , now when i go to use the new key it turns over , revs for one second , then dies , saying check engine , the old key still works fine , is there a way to teach the new key to start the engine , i know each key has a transponder in it .
Someone must know plz !!!
CLASSIC IMPREZA TURBO 2000

 

Had to take mine to a Subaru garage to code it...Charged me £45 too.....