I have a 2006 dodge 2500 4x4 5.9 cummins and I get a check engine light only in cold weather low voltage circuit a can't figure out truck doesn't perform any different runs fine can anyone help me figure it out

 

what's your code number, is it injector circuit?

 

P0642

 

That's the only thing that comes up only in cold weather summer doesn't come on

 

alright, its a sensor supply code, ill have to pull a schematic and see what sensors run off that supply, I'm guessing its a temp sensor and its bad enough that the cold weather shorts it out, once it warms up it quits shorting

 

base on code description it looks like only the fan runs this circuit, inspect the fan harness where it goes up between the radiator and the fan and see if its rubbing anything

 

I'll do that

 

I've checked the wires nothing seems to be rubbing for thr first time another code came up p0069 I need to mention I bought this truck five years ago it has a live tunner in it with a air dog filter and has done this every year would that have anything to do with these codes

 

imp surprised it doesn't run different, the baro/map sensors are crucial for fueling, mines setting a map code right now has zero power and no boost at all

 

It has a boost fooler would that cause a problem i unplugged it sometime back didn't make any difference