Keeping it short, I have the P0420(Catalyst System Efficiency Below Threshold) error code locked into my 2000 Civic LX. I've tried resetting, but it returns shortly after. The engine has only 4k miles on it, but the rest of the car has about 100k. Maybe I messed up the timing. You can read about the error here: OBD-II Trouble Code: P0420 Catalyst System Efficiency Below Threshold (Bank 1) Symptoms include: -Stinky white smoke -Surges during acceleration/idle -AC on = SLUGGISH! Have to stay down an entire gear basically. The front 02 sensor wires are spliced, so I'll check up on that first. Other than that it will be a bunch of testing, but hopefully I can get some sort of help from all of you =).