Pontiac Problems? Ask a Mechanic for Answers ASAP
Hello, my name is***** your check engine light on?
Does vehicle idle good or idle rough?
Vehicle still won't go past 40 mph? P0405 usually is related to the EGR. As of right now I think converter was main problem but EGR is also bad.
Have you done another exhaust pressure test? It sounds like you may have a clogged muffler or resonator.
Either sensor is fine. A quick test is to remove the front oxygen sensor completely from exhaust and open hole will relieve pressure. If this allows rpm to go above 2500 rpm you know exhaust is clogged somewhere. Let me know how it goes or if you have more questions, thanks.