Got a 2012 3500, I've noticed that when I let off the throttle to shift or just let off at any time that my rail pressure will spike to around 21k.

It won't do it all the time, just sporadically.

I'm wondering what might be the cause, I have no check engine lights or any other engine problems.

I'd just like to address this issue before it becomes a bigger one (and have to result to driving my powerstroke).

I'm not new to diesel but this is my first common rail.

Thanks.