My sister has a 98. 5 manual 235hp. The check engine light has been coming on and resetting itself for 6+ months. When it is on there are no symptoms. Still has power. She said she did notice a slight stumble when accelerating in 3rd a couple days ago. She took it to the local 5 star who stated that it showed a "timing code". They quoted $2500 for vp-44, filter, and new lift pump.
(they say although LP pressure is good, it is leaking. )
Here is what we know.
-LP has been good since her ownership(2 yrs) I installed gauges when she got it.
- Filter has been changed regular, (PSI gauge is post filter)
-light will always activate when we tow
-cummins e-brake, but I keep IAT clean, and light will still come on w/freshly cleaned IAT
By searching here, my thought is to change the $25. 00 crank sensor, and see how things go.
Any thoughts please

Here is what we know.
-LP has been good since her ownership(2 yrs) I installed gauges when she got it.
- Filter has been changed regular, (PSI gauge is post filter)
-light will always activate when we tow
-cummins e-brake, but I keep IAT clean, and light will still come on w/freshly cleaned IAT
By searching here, my thought is to change the $25. 00 crank sensor, and see how things go.
Any thoughts please