• Got the Contributing Memberships stuff finally worked out and made up a thread as a sort of "How-To" to help people figure out how to participate. So if you need help figuring it out, here's the thread you need to take a look at -> http://www.corvetteflorida.com/forums/showthread.php?t=3581 Thank you, everyone! Rich Z.

CODE...PO420HC

zzzona

zzzona

New member
TWC System Low Efficiency bank 1...
Does anyone have any idea as to what keeps causing this code to pop back up... I have taken out the Oxy sensors and cleaned them, cleared the code and about 3-4 hundred miles later it comes back. If I clear the code and don't clean the sensors it will throw it in about 50 miles.
I have
Headers R/T cats.....
 
I guess you could get O2 simulators or just have those codes programmed out. If I remember how this works, I believe the rear O2 sensors are just tattletales to make sure the cats are working properly. The headers are more efficient at moving exhaust down the pipes, so the sensors just don't know how to handle the change in exhaust.

I get odd codes thrown now and again, but only if I am driving the C5Z real slow in first gear for a length of time. I think the car is just complaining... :hehehe:
 
Rich Z said:
I guess you could get O2 simulators or just have those codes programmed out.

I talked to FRC TOM and he will re-program and delete this. He did the original tune.:thumbsup:. He said this is a common problem with R/T cats and headers...I pulled the sensors out yesterday and the right bank was black with carbon, but the left bank was clean...Does not seem to effect how the car runs, just throws the code...
Click to expand...
 
zzzona said:
TWC System Low Efficiency bank 1...
Does anyone have any idea as to what keeps causing this code to pop back up... I have taken out the Oxy sensors and cleaned them, cleared the code and about 3-4 hundred miles later it comes back. If I clear the code and don't clean the sensors it will throw it in about 50 miles.
I have
Headers R/T cats.....
Click to expand...

PO420 is not a O2 sensor problem. It's low flow secondary air on bank 1 [left side]. Are the hoses all hooked back up correctly? Is the check valve base tight and gasket good [if not you may end up with a bank 1 lean fault also]? Check the hose that comes off the left side check valve that goes to the "T" on the left side from the pump to make sure it's not pinched/off/cut/etc.
This may not be incorrect 100% of the time, P420 is cat inefficient, which is very common with hi flow cats or no cats at all. a tune or o2 sims will clear this up.

:D Jim :D
 
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