This’ll be a long one so if anyone has the time much appreciated, 

Bought a 08 accord V6 automatic with 150k back in November from a private party, only problem was a worn suspension and a leaking power steering pump which both got fixed. Was welcomed with a below threshold bank 2 cat code about a month later which I got replaced with a cheap cat I found on eBay, since then I have done the usual oil change, spark plugs, air intake, trans drain and fill (you get the idea). I keep up with my fluids and add when needed. I did also get into an accident in January which took out the passenger headlight and fender which has also been fixed with no damage to the interior. 

Now for the fun part, 

For the past month I’ve had a P0174 code which is fine (not really), but this code is a bit special. The check engine light will pop up randomly and when it’s not on the dash the code is still there until I erase it. To try and fix this I have: Checked throughly for any vacuum leaks or gashes, cleaned the MAF sensor twice, re clamped the air intake, changed the O2 sensors twice, checked the PCV valve, and checked the fuel filter. I have even recently installed a VCM muzzler because I’m not a fan of it, which got rid of the code for a couple days. 

When taken to my mechanic after some research he told me that my O2 sensors weren’t compatible enough with my car, saying I need Denso brand sensors instead of the NTK (NGK) brand I just recently put in. 

Now my question for you all: Before I spend another 150$ on both sensors again, could this actually be the reasoning behind the code? Is the catalytic converter I bought too cheap for my car ? I wouldn’t call myself a mechanic and I do trust mine, but I’m a bit skeptical it could be something else I’m missing. If anyone has any questions I’d be happy to answer and I apologize for this being so long, thanks again.