Hissing sound on firewall right side? You mean as you're looking at it? Driver's side? Maybe it's a leaking brake booster.

 

yea drivers side , late night could not think with toddlers and wife in my ear . would that cause the other codes to pop up

 

I don't have my code list with me right now... what's 12, EGR? I don't think it'll cause that. Vacuum leak would cause surging idle, & some of that stuff.

There's a vacuum hose from the intake manifold back to the vacuum-booster at the brake master-cylinder. Anything leaking in that hose? There's a plastic check-valve in that hose, that might be broken? Check that stuff out; maybe try to pinpoint the location of the hissing sound.

 

I had to deal with a code 12 recently, that's for EGR lift sensor. I understood it as meaning the ECU requested that the valve be lifted/opened but when it polls the valve lift sensor it finds that the valve hasn't actually gone up and throws the code.

The thing about this is that it could be because the EGR diaphragm is torn and it can't hold a vacuum OR it could be a problem with the vacuum coming to the EGR valve. In our case the EGR valve was tested for vacuum and it held. We traced the lines and found an unplugged line which was plugged in and got rid of the code. So the EGR valve couldn't lift even though it could hold vacuum because a line in the stream was unplugged.

So if his EGR valve holds a vacuum (something he can test easily) in the presence of this code I think he has a vacuum leak of some sort due to the fact that the EGR valve is not lifting even though vacuum is good.

If you want to test the EGR valve for vacuum, just unplug the vacuum hose that goes in to it, pull up on the diaphragm, plug that hole the vacuum hose was on, let go of diaphragm while holding over that hole. The diaphragm should not come down. If it comes down even though you have your finger over that hole, it means the diaphragm is not air tight and the valve should be replaced.

 

Well, if that's it, the EGR being a vacuum-leak might cause some of that other stuff. Worth a good look at vacuum hoses etc.