Hi Guys,
I'been getting gray hair cause of this. I got "service engine soon" burning. Before there was one active code, water temp sensor 15. Put in a new one. Now I have 23 "air intake sensor error". Well I'm pretty sure that this old 6.2 doesn't have one...Right?? There's more. After checking this code (with jump wire) it's gone. But after some driving it gets back.
Also have this issue with OD jumping on and off but that's a different story (hope that OD problem was related to error 15 but as it now seems after few test runs OD problem still exists).

 

You may be looking at gas engine codes. Many codes are different on the diesels, although I haven't seen a list for 6.2 only 6.5. I think 23 is accelerator pedal position.

If you haven't already, I'd recommend cleaning all grounds and battery cables. Replace anything that's iffy. I have two early 6.5 trucks and it's shocking how many issues this clears up.

 

Hi,
and thanks burnhedge. Happy to be the "dumb" guy here. I think this solved my OD on/off issue as well. It's my first GM diesel, everything is learning the hard way (now I have the codes for diesel). Also good point to go through the ground cables. Thanks again!