99canadahawk

I have a code coming up as P0420 ( cat efficenty system below normal bank 1 ) a month after my headers were installed & the car was tuned but I don`t know if the tuner had the O2s deleted from the system , I did have the front driver O2 replaced for running lean . Could it be the cat ? its new and came with the headers , anyone heard of any problems with SLP bullet cats ??

Thanks .

2TR

Reason: The oxygen sensors in front and behind the converter are reporting too similar of readings.

Fix: You need to turn OFF the DTC for the rear 02's using the tuning software.

99canadahawk

Thanks 2TR , So you think I need to have my rear 02`s turned off then ? it makes sense I don`t think it could be the rear o2 or a cat gone bad & I don`t recall my tuner telling me they were ever turned off so sounds like a good place to start BTW what does DTC stand for ??
Thanks !!

2TR

Appears your front 02's and rear 02's are communicating with each other showing a similar reading from precat sensor to aftercat sensor (gutted or no cats?) thus posting the P0420 code.

DTC = Diagnostic Trouble Code

99canadahawk

Ok gotcha , could it be possilbe that it`s a bad rear O2 causing the code to pop up ? It`s just that Ive been talking to some techs at work and they keep telling me to change the O2 first and see if it fixes the problem ? ( but @ $180+ its kinda an expensive trial and error if you ask me ) and would I have to get it fully re-tuned again just to turn off the O2`s ?
Thanks again for the help I`m just not sure wich route to take ???

WICKED_Z

It wouldn't require a full tune,just turning 4 dtc's off to not report errors. Someone correct me if i'm wrong

99canadahawk

Ok now we`er getting somewhere ! the only reason I asked about the full tune was that I heard it from a friend of mine saying it needed to be done because of the A/F ratio would be out or something ?? but it really does not make sense like you have stated . Anyways had the car e-tesed ( with the CEL on ) & did not pass out by 3 hydrocarbons , I was also wondering if I had temp cleared the CEL for the e-test would I`ve passed. ..maybe ?? I`m going to try and get a hold of my tuner soon so we can fix this problem !!! . . .

WICKED_Z

Not sure where or how the back 2 o2's would cause the a/f to go out?
All the back two o2's sensors do is tell the pcm,hey cats are working dont set the ses light.
The two front o2's control the a/f.

Old Geezer

iTrader: (3)

I have seen many instances with "hi flo" cats turning on the SES..The comparison of readings from ft to rear O2's can be the problem. AIRC, that's where the "sims" came to be a "fix"...At least until the Feds got involved, that is.

99canadahawk

Thanks for everyones help !!! I had my tuner turn off my rear O2`s and clear the CEL everything is good to go !! But. . . . My hi flo cats are not hepling me pass emissions now so I think I will need to replace my '' new SLP cats '' that came with my headers with some Magnaflow heavy metal ones .