CEL codes p0421 and u0100

[jallways]

Anyone throw both those codes after fuel pump internals install?

[atvfreek]

No, but I believe there is a firmare update for the ap that takes care of the u0100 code. And you can get rid of the p0421 code with ATR

[VT2WA]

Whose internals did you get?

[jallways]

Autotech

[osmar_21]

got the same problem. car wont start.

[Shadow]

are you running a catless or high flow cat? p0421 is cat failure. the u0100 code should be the update like was said previously, if your running a catless dp or high flow catted dp it will throw a 421, just use atr, turn off monitoring 420/421. It should be done already if your running stage 2 unless your running ancient maps.

[Pat Attack96]

Other than buying an AP....how else can you get rid of the P0421 code??? I have heard rumors of dummy sensors that will do that? I will have a code reader that can clear codes but if the root cause isn't fixed the check engine light will come on in a matter of time...

Thanks!

[zumanback]

Bumpity bump. Have read all the threads on this but still can't determine what may be causing the issue. I do not have an exhaust leak BTW. I would hate to buy a new 02 sensor and then still have the code showing up (which i have read over and over happens).

Suggestions?

[MSMS3]

Suggestions: Yes. List your mods (all of them that are power related), especially on the exhaust side, describe when the code started, and what you’ve already done to try to resolve the issue.

You are asking us to be mind readers with nothing to go on but the P0421.

[Jeff23spl]

o2 sensors are wearing out parts that need replacement one day or another...
if you have the main wideband one, it cannot be fooled with a bung extension because it drive the whole system afr...And no it isn't something often happening, it will happen often if you keep erasing the code without repairing it but once repaired it won't come back.
For the second probe, it is mostly there to watch if you remove the cat, you need to fool it in some way by either cancel the trigger with a cobb ap or try the bung extension that didn't worked for my 6 and cobb DP...i dont remember which exact code i was getting but it was related only to the second probe.