I bought a 2003 CTD and the airbag light is on. Pulled up the code p0477 exhaust pressure control relay low. Anybody know what this means? Could it have something to do with the edje juice?

 

Mine has recently thrown this code. At the same time, my jake brake quit working. I looked up the brake manual and it says something about not reaading 12v on a certain pin going to the ecu. I dont have the pdf file from Jacobs anymore so I cant be specific, but I remember the code being specifically mentioned.