"Reduced engine power"
 

Is there anyway to do a custom tune to prevent the truck from going into this mode? It looks like finding the actual cause is going to be difficult. It's my brothers truck. 06 2500HD with 6.0. Runs great except for this issue which will about get you run over on the Interstate. Pull over and turn off the truck and it runs fine again. Throttle body(local shop said that was the problem along with needing all 8 coil packs replaced) has been replaced but that evidently wasn't the problem.

Truck is bone stock.

Re: "Reduced engine power"
 

If you are getting that message, you should be getting some codes. Swing into a parts store and have them read the codes, then post them up.

Re: "Reduced engine power"
 

Broken wires at the throttle body connector is very common on these trucks & it will cause the "reduced enging power" messege on the cluster...AND set throttle body codes, Take the coils & throttle body back for a refund. Dont ever use that "shop" again either.....Scan tools are a tool just like a wrench...They ARE NOT replacement for experienced automotive technicians.

Untape the harness back about 6 inches from the throttle body. Lightly pull on each wire individually.....the one that stretches is the broken one.

Re: "Reduced engine power"
 

Thanks for the replies. He has a scanner so I'll get him to post them or I'll post em. He didn't get any coil packs. I didn't think that was the problem. He's tried to find a broken wire but hasn't untaped anything. That may be a plan.

Re: "Reduced engine power"
 

Agree that most likely the issue is in the connector to the throttle body. Check the codes if they are throttle position related than purchase the new connector pigtail from local dealer. Who ever installs make sure to solder dont use the butt connectors supplied with the kit. Also keep all wires the same length. The wiring is the most common problem.