http://www.7thgencivic.com/forums/sh...d.php?t=182026
refer to this list anytime you have a check engine light. Now the 3 codes you have are
P1298: Electrical load detector (eld) circuit high voltage
P1259: VTEC system malfunction
P0420: Catalyst System efficency below threshold
I dont really know what you have on your car because you didnt really say much, but all 3 codes are all different from each other. if you want I can go through the troubleshooting for each code for you, P1298 and P1259 will require a bit of diagnosing to figure out the problem, as P0420 is something that takes about 5 minutes to figure out. P0420 is for your cat converter and it is either bad or you have a intermittent failure. P1259 has to do with your VTEC system and P1298 has to do with the electrical load detector circuit in the fuse box.
Now if you had the car at the mechanic for him to fix your problem, then why didnt he fix it? 2 of those codes have nothing to do with aftermarket lights or amps. Maybe you need a new mechanic.