These codes show up every so often on my 05 with shorty headers & Random Tech cats & x pipe.

There are no leaks, O2 sensor issues etc.
I understand these are nuisance codes, even occurring with an OEM exhaust system.

Is it true a Tech II can turn off the reporting/ signaling, by the check engine light illumination, of this code?
Is there a TSB?
Any issues/ potential fires (haha) if I turn off the code reporting?

Any comments?

 

Sorry, but there is an issue that is caused by your exhaust additions. The rear O2 sensors are not reacting per the expected OEM programming due to the exhaust changes. Don't know anything about the Tech II, but any person doing custom tuning can shut the rear O2s off so they will not report an error code. It can also be done with HPTuners or other such programming systems.

The rear O2s are there to give an indication of catalytic converter efficiency, so you will lose that indicator if you turn them off. If the converters become clogged you will not know until they are so clogged they impede engine performance.

 

Probably SHOULDN'T turn off anything until you diagnose your issue and make sure your Cats are "storing" oxygen as they should....watch the video...you'll need a scan tool to properly diagnose this !!

 

P0420 Catalyst System Low Efficiency Bank 1 ECM
P0430 Catalyst System Low Efficiency Bank 2 ECM

So lets break this down and go into some greater detail.

The post O2 sensors after the cats, are used only to monitor the efficiency of the OEM cats only. The pre-o2 sensors are used for closed loop, and the rear OS sensor readings are only used to see how well the cats are working isntead.

Move the stock cats farther away from the heat source (heads) and you lower their efficiency of the cat. Change from the OEM cats to high flow cats, and you just lowered the efficiency of the cats even more. So again, pre and post sensor reading are used to see how well the cats are working, and if the differential readings are not great enough between the pre and post sensors, you get the codes.

So this is a know problem with headers and high flow cats, you have one of two choices.
1. Don't use the rear O2 sensor and just turn them off in the tune.
2. Use anti foulers for the rear O2 sensor to pull them out of the flow of the exhaust, so the give lower readings, and make the cats look like they are working more efficient instead.

Since Headers will scavenge the exhaust better and cause the engine to run leaner, when the car is re-tuned for the headers to get all the power of them and the motor, you just turn off the rear OS sensor in the tune to solve the 420 and 430 code problems. Hence don't even bother to install the rear o2 sensor and just plug any bungs that you have for them in the system instead.
Note, you can not turn the rear OS sensors off with a tech II since it only allows ECM firmware flashing, butt not ECM firmware tweaking isntead. So it takes tuning software like HP tuner, EFI live, ect that will mod the ECM files to begin with.

If your waiting to have the car tuned, and what to solve the problem short term with the rear o2 sensors in play, then anti foulers on the rear o2 sensor are the item of choice short term instead. The reason that I say short term, is the car really need to be re-tuned to take advantage of the long tube headers, and the rear OS sensors can be turned off in the tune then as well.

Here are what anti fouler look like and again, just pull the rear O2 sensor out of the exhaust stream to make the cats look like they are working more efficiency so you don't get the lower differential readings between the pre and post 0s sensor to cause the codes.

 

I calibrated a 2015 ZL1 Camaro yesterday. The owner added Kooks long tube headers, High Flow cats, and an air intake. He had them on for more than a month before I calibrated it. I was surprised the only code he was throwing was the P015D code. No cat related codes. I usually see that code caused by the extender harness for the front O2s

 

Here's a follow up....maybe a little late, yet I just did this fix yesterday.
I followed Dano's advice and installed the anti foulers.
Seems to have worked.

1) Napa Auto Parts # NOE 730-2442 $6.89 for two (need four) and includes 2 gaskets per set.
Note the fouler size is 18mm (not the 14mm.)
2) Two foulers used on each side screwed together with gasket/ seal in between the two.
3) Take one of the two joulers and enlarge/ drill out the hole to 1/2 inch (to perfect fit the O2 length) before screwing the foulers together.
4) Disconnect the O2 from the harness (easy) note the metal retaining clip on the driver sided and a push in plastic clip pass side that retains the harness's electrical connector.
5) Install O2 sensor in fouler with gasket between the fouler and O2.
6) Install fouler and O2 into exhaust pipe with new gasket between pipe and fouler.
7) Note: I used anti seize on all threads, take care to not get any anti seize on the O2 sensors.
8) Note: I hand tightened firmly...no torque specs....I guess 20-35 ft pounds
9) Note: Used hand tool wrenches and this worked fine, not sockets, with plenty of room for ones hands and the wrenches.

No drivability differences felt, runs as good as before.
No check engine light (so far with in town/ highway 20 mile test drive). Will need to take a 100 mile to confirm.
Unknown if this mod will fail a Calif OBD smog check, will find out at next registration renewal.
The foulers seem to be a good mod with much written on the net that this mod works and stops the P420/ P430 codes from setting.

Thanks to all who replied