Today my truck died about a mile from my house on my way to work. It wasnt even warmed up yet. The truck tries but wont start at all. My pedal went dead and the truck just died.

I scanned it and got a p1688 code (injection pump) and a p0237 code (apps sensor). Ive searched all morning because I want to make sure it's an injection pump that I need or if it could somehow be the apps sensor that is throwing things off.

My truck has always had great fuel pressure 15-20 psi provided by my Glacier Diesel Fuel Boss and I have 2 gauges to monitor it while driving. Just stumped with both codes.

Thanks for any help!

1999 24v Cummins / 5spd with dual disc Southbend clutch, edge comp, s&b intake, Glacier Diesel Fuel Boss mechanical lift pump.