Fault code 67 on 99 civic ECU
 

I bought a greddy 421 header and the CEL came on. It's throwing a fault code 67 which is: Catalyst system Efficiency Below Threshold malfunctioning or defective catalyst system. I wanted to know if anyone could tell me what to do from here.

Re: Fault code 67 on 99 civic ECU (civicsi21)
 

normal code for OBD2 vehicles when changing something on your exhaust system. the OBD2 cat code is real sensitive when it detects changes in the exhaust system. Don't worry, it won't hurt your vehicles performance..