Hey guy. I have just a set of custom 3" Cattman headers on the car and 2.5" cat back with a test pipe. Everything worked fine while boosting. Now all the boost is gone. O2 sim on the back O2.
Will any of these code cause the car to go into safe mode (no rev more than 2800 rpm's)
Anybody have this happen to them. The car had less problems when I was boosting. Go figure.

 

You don't have your vehicle information in your profile (nor state it anywhere in your post), so I'm going to assume you have a 5th gen.

According to the FSM, P0403 will induce safe mode, yes.

Have you done any diagnostics at all? Looked at it? That's the only way you're going to find if something was unplugged or damaged to throw these codes.

 

Yes it is a 5th gen 2000 maxima. Ok so I need to see whats up with the EGR valve. If it is not a wiring issue, could the valve be bad?