Is your truck tuned at all? With what. I ask because I've had a customer come to get tuned - I downloaded his stock tune and compared it to another customer's stock tune with the same OS and truck equipped exactly the same. They had no difference that EFI Live could find and I loaded the DSP5 tune I already had for the other customer onto this truck. Everything worked fine, no check engine light or anything but we noticed the oil pressure gauge wasn't working. Tuned it back to stock and it worked fine again. Built a new DSP5 tune from his stock tune, loaded it on and it worked fine. Compared his new DSP5 tune to the one that made the oil pressure gauge not work and EFI Live could find no differences. This is why I write every tune starting with that trucks stock tune now, regardless of OS or whether EFI Live says they are identical stock tunes.