I have a 2008 2500 HD with the 6.0 gas motor. I was driving the truck and the check engine light came on and the truck lost power. I limped it home and found the drivers side cylinders were not firing. I have changed the coils, spark plugs, wires and the ECM. Also checked the fuses in the box that go to that circuit. I don't know what to look at now? I believe it is a electrical just don't know were to start?

 

Can you give us some OBD II codes?

 

codes
p0351
p0357
p0357
p0355

 

Sounds to me like a Faulty Powertrain Control Module (PCM).

 

Already replaced the ECM. That was the first thing I did.

 

Could have a bad MAP sensor. They can sometimes be cleaned with brake cleaner if dirty or the connection
has some corrosion.

It's usually a code P0106, but it's possible it won't show a code.

Did some more research on your issue, and it was the O2 sensors that were the issue.