Honda Repair: 1999 honda accord cat converter, auto repair shop, cat converter

Question
Hello,

My boyfriend has a 99 honda accord shift stick that within the last month has had the cat converter replaced. (One he purchased online) Since then when he drives over 40 mph the car makes a loud humming noise. The check engine light came on. He said he could not see a hole in the muffler. What could be the cause of this problem?

Answer
The first thing to do is get that code read. I'm guessing that the humming noise and the check engine light are both caused by the same thing, but they might not be. Most likely the cat was either not installed properly or it is the wrong one or it is a cheapo one that is no good.
Get the code read first (you can have this done for free at most any auto repair shop) and go from there.
You can find the definition of the code from my website:

http://www.myautorepairadvice.com/obd_codes.htm