Hey guys I've got a 2004 6.0 Excursion and I am trying to get it to pass smog in California. All of the emissions equipment is intact but I keep getting a p0487 code. I recently replaced my intake elbow and egr throttle valve with an 05 intake elbow that deletes the throttle valve, but put it back on for smog purposes. When it was off, I always got a p0488 code, but when I put it all back on I get a p0487, and occasionally a p1408 code. My edge insight also shows 0 psi on my Exhaust backpressure sensor, which I'm not sure is related or not. I cannot get that p0487 code to go away, causing me to fail my smog test.
Any help trying to figure this out would be appreciated.
Thanks