P0420 and p0430

[robertmee]

Seems I have two bad cats :eek:

However, the cats are brand new High Flows from Magnaflow. Well not BRAND new, but less than 500 miles on them. As is the new Stainless Works Long Tubes, Borla mufflers and X-Over. A reputable custom muffler shop installed it all.

I have an AutoIngenuity scan tool and trended the O2 sensors and the waveforms look okay there. All four are running sinusoidal. But should the O2s AFTER the cats be more flatlined? When I googled and read on the codes, it mentioned that the codes are thrown if the before/after O2s are similar in waveform. I'm going to trend them again on top of each other, but in the meantime.....

I would assume an exhaust leak at one header isn't going to cause the other bank to register, so what other 'common' component could effect BOTH banks and cause the two codes?

Note: The codes did not reset themselves after a week.

[Comin' in Hot]

did you get a new tune after the LT and cat install?

[ctrlraven]

I believe Lidio does turn off the rear O2 sensors in his tunes also.

[robertmee]

did you get a new tune after the LT and cat install?

Yes....Fastlane Motorsports in Benson, NC Dyno tuned it. 463 RWHP :)

[robertmee]

Just talked to my tuner and they said they can also turn off the 2nd cats but wasn't sure if that affected the inspection readiness for Marauders. He said for 2005 Mustangs and up that turning off the back cats does.

If Lidio is turning his off, I assume it's okay?

[capt512]

I know thier have been threads about people having to remove lidios tunes before inspections as the cats arent being read and fail the computers.

[STEPS]

What tuner are you using for the new LTH ?

[SpartaPerformance]

I find it hard to believe that you would have 2 bad cats. What does your A/F ratio look like after this dyno tune?

[robertmee]

What tuner are you using for the new LTH ?

Fastlane Motorsports is the tunee....the Tuner is my handheld SCT Xcal2

[lttljp15]

i have a 420 and 430 comes up about every 800miles with LT headers and high flow cat from SW, could a slight misfire cause this code?? it was tune before i bought it, and i think it was tuned for a CAI which isnt on the car anymore.