There's a crack in the stock headers where the o2 sensor is to the other side of the headers. I looked at other civics in the junk yard with the d16 motor and all of them seem to have been cracked in the same place. Is it very common?

My car is reving between 1000 and 2000 in neutral. It drives fine on the highway. I rebuilt the throttle body. I haven't changed the o2 sensor or cat sensor. The engine light is on and it gave me a few codes. One was for the o2 sensor. I am wondering if it would be the o2 sensor causing the reving or what else could it be (i.e. vacuum leak)? And what would be the ways to check the different possibilities? Thanks in advance. I am very lost, I am used to b18.

 

It is common. Replace the cracked header.

 

Get an aftermarket header.


Post up all your codes so we can go from there.