I've been chasing a persistent Check Engine Light since I bought this damn car, 3 years old and 42k miles on it.
2005 GP Base. Nothing special. P0420, Catalyst Efficiency Below Threshold, Bank 1, bank 2 occasionally.
I bought a catted DP from ZZP. I did a resonator delete, and recessed the rear O2 sensor while I was in there. Aside from a properly prepped drop-in K&N filter, these are the only mods. All was well for 6+ months, now I'm getting the P0420/Bank 1 code again, persistently. Bank 2 is fine, so I know the recess job is working at least.
Seriously...I'm about fed up. I've spent $1000's in diagnostics and letting my mechanic tinker, as well as the parts themselves. Everything from new plugs/wires/coils, new MAF, new EGR, new PCV, 4 (yes FOUR!) sets of new AC Delco o2 sensors. In all I'm probably in for half of what I bought the car for, by now, chasing this one damned code. It would be cheaper to fire up the $400/month payments on a new car at this point.
I'm missing something, aren't I? I really need some help here. I love my Prix but ...I can't renew my registration with a MIL. I'm not particularly mechanically inclined (I can change my own fluids, brake pads, etc, but I don't have the place or tools to do the hardcore stuff) so any help is greatly appreciated guys.
