I have a 06 cummins, when the temp drops below 10 deg. it wont crank, I treated the fuel but still same problem it also throws a P2509 code, the batteries are new. any thoughts why it does this in real cold temps?

 

Get your batteries load tested. Make sure you unhook the battery cables so they get tested individually. Many auto parts stores will check batteries for free.

 

I have a similar issue with the P2609 code. It only occurs under 2 conditions:
1.Decelerating from highway speed (65-75 MPH) to exit the highway.
2.Coasting on a secondary road in 4th gear to enter my driveway.

The DTC message is "No voltage drop seen from intake air heater"

Here's what happens:
The wait to start light goes on and the truck chimes. Until I clear the code using my Smarty Jr.the light stays on and the engine loses power. What's interesting is sometimes there's no DTC code but clearing the non-existant code temporarily fixes the problem.

Since I have the intake air preheater delete I put a 6-ohm 50-watt resistor in line where the preheater should be. This didn't fix the problem and I should note the problem didn't occur until about a year after doing the delete.

I'm was wondering if something else applies to my situation. Does anyone have any idea if there's a TSB to fix the issue? Perhaps there is a way with the Starscan tool to disable the computer from looking for the voltage drop.

I can live with the annoying chime but the power loss in unacceptable...
Thanks,
Jonny