P0174 BMW - I have no cats due to a racing header, could this cause code?

Question

I have no cats due to a racing header, as such it throws o2 codes all the time but it has recently thrown p0174, could this be caused by the lamba or is it more likely to be vacuum/maf related. Headers have been on for over a year.
If i wipe the code it can take over a week to retrip. I will clean the maf n give the filter a good clean but is it likely to be an o2 exhaust sensor or something intake side causing this rather than exhaust side?

Thanx

Answer 1

Most likely this is being caused by an intake leak. Possible the maf is the issue,although normally we see 171 and 174 running together if it's the issue.I would check the intake for leaks along with all the vacuum hoses.