PO231 Code,and PO603 code

[907DAVE]

P0603 is because of your chip - normal condition and there is no need to worry about it.

P0231 can be cause by many issues, but if the truck is still running (fuel pump works) the condition is intermittent.

A few possible causes are....

* FPM circuit is open or it is shorted to ground
* Fuel pump relay output circuit (VPWR) is open
* Fuel pump relay has failed (no output voltage)
* PCM has failed
* Inertia Switch open
* Fuse box (rusted from water intrusion)