my friend whants to sell me his 1992 volvo 240 for 600$ but it wont pass emissions the car drive fine its been to the cape a couple of times whith no problem at all its a little loude around the cat but we just got the muffler fixed its alloriginal stuff on it can sombody give me an idear on what it might be so i dont half to spen 60$ on trying to find iti think itsmight be eather o2 nox or somthing else thanks i apreacit the help