this code is a common problem on newer hondas, If you get it Honda will replace the cat. convertor for free under an extended powertrain warr, In CA, I think it's now 7/75k or like 10/100k You have to call to find out. I replace a lot of these cat. converters under warr. If the aftermarket cat. convertor was put in and that code came on the cat. is probably bad or not reducing emissions enough to the computers programed levels. Your accord looks like a 98-00 model from the picture, it's probably a ulev car or at least a lev car. It's programed to have lower emissions so if the aftermarket cat. wasn't doing a good job of cleaning up the emissons the computer will throw the code. If you don't know on that car the front o2 and the rear o2 measure the exhuast gasses and the computer compares the readings. By comparing the reading it determines the effienticy of the cat. You can check the o2's by looking at them in a scanning like snap-on's advantage scanner or another brand. In the live data list screen you can watch the fuel trim and o2 sensors while it's running to see if they work before replacing the cat. I know your car is fixed now but for others reading this in the future I thought I would post it. Anyways honda has a problem with late model cats too so even if it has passed the regular warr. it should be covered.