Installed catless UEL BORLA headers, got a CEL that you wouldn't expect (NOT P0420)
 

Hi guys, last friday I installed BORLA UEL catless headers, and got a CEL light 2 days later, code P0171, for 'running lean'. :bonk:

There are MANY others using the same tune im running (A stage 2 UEL catless tune, with delayed low load ignition for pops/bangs out exhaust).

However, i'm pretty sure I have a leak from the passenger side (AUDM) header gasket (which sounds a bit like a puff/ticking sound).

My question is, would I have gotten this CEL code due to having this leak?

Cheers

Yes the CEL is likely related to the exhaust leak. The front sensor is seeing higher O2 than expected (AFR) and has maxed out LTFT. Once the ECU can't adjust fuel trims any further it will throw that code. You may also notice that the exhaust is actually smelling super rich.

I just checked it out, and here is the result:

[ame="https://www.youtube.com/watch?v=bSF9nc62WuE"]Leak1 - YouTube[/ame]



Part in the video is show in this pic:

https://image.ibb.co/nqUvwv/header.png

bump

Dude, the answer was already given to you.

Do you want more people to confirm? If yes, please reply with the number of replies you want to get so we can answer your question definitively.

Yes I would like some more people to confirm, that was the purpose of the bump. Maybe someone else has had the same experience.

https://www.google.com/search?q=p0171+code

You already confirmed you have a leaking header so it's really up to you if you want to accept the diagnosis and fix it, or leave it as-is while you wait for internet keyboard warriors to confirm or not.

But if you want to build up your confirm karma points, my answer is yes.

Bump for what? Did you fix the leak yet? You still have the code after the leak got fixed?

Did you use new gaskets? Did you tighten the nuts with a torque wrench with the correct torque?

Get off the internet and go fix your exhaust leak. :D

I will do lol. Just wanted some more confirmation in the meantime, as I can't fix it for a few days.

Bump for updates.

Got same code, ignored it.
Car now has AIDS.

Ok tried tightening that nut, but its very hard to access, managed maybe a quarter turn of tightening with a spanner, and the leak sounds like it halved in loudness.

Any downsides to using gasket sealant to finish off?