Hi guys i need help once again...ever since i swapped a b20z engine on my 94 integra its been throwing me a check engine light but only after a few minutes of driving the car (Specially when i get on the highway). I did a check on the computer and it throws an engine code: 43
... I think i need a new o2 sensor?? Am i supossing right?

Things on the car:i/h/e, fpr (around 45 psi i believe, on iddle i don't remember but obviously less) ,ls intake mani.

I haven't tuned my car since the swap, but i will do it right after i install the 403 cams and valvetrain i got .

Try a stock FPR.

it's o2 or can be fuel system. I say replace the o2 sensor.

i am gonna try the o2 sensor first... i'll see what happens.

Try adding like oil if it needs it. fixed my CEL lol.

He has retreived the code, so how will oil help a code related to fuel?

Do a compression test, low compression in one cylinder may cause a missfire and lead to an O2 sensor code.

Problem fixed by changing the o2 sensor
thanks to everyone that suggested ideas .