p0422 code

Ok I got this code messing with me.Something about below cytalyst threshold on bank 1. Two years ago the car was repaired by the dealership for low compression in cyclinder 2 and a new MAF was installed at the time and a tuneup.I have replaced the 02 sensor before the cytalyst.New timing belt,air filter,V-belts,Thermostat,Fuel Filter,New OEM gas cap and keep the oil changed on a regular basis.I just recently checked cyclinder compression in all cyclinders AVG. 175 so what is it I need to do now? Please Help need to get through DEQ soon. 2000 accent gl 1.5l 12v sohc