I just installed PPE pyro and boost gauge. Everything seems to be working ok when driving the truck. When I shut the truck off the pyro gauge stays around 200. When I turn the key to on position the gauge lights up and the needle zero's out. If the truck is cold it will stay at zero. If it is warm then it will read what I think is the residual heat in the manifold. It's probably ok, it just seems this gauge should go to zero when the truck is shut off. Could i have a bad gauge or sensor??? Any input or suggestion would be much appreciated.