Reduced power mode, check engine light

[Dougm]

Hi;
I am new to the Diesel Page. Have 2004 GMC w/LLY engine. Runs great @ 35,000 miles. Had engine go into reduced power mode & check engine light come on. Not towing. After engine restarted power restored. After several starts check engine goes off. Dealer said code showed reduced power mode activated. Could find no problems. Suggested my added bed tank could be problem. One month later did again while pulling our Alpenlite up steep grade in Nevada. Restarting cured problem. Makes us nervous. Any ideas?

[More Power]

There are several possibilities for a "limp mode" or reduced power mode. Would be helpful to know what codes were being set.

Your local Auto Zone parts store can read the codes for you or you can buy one of the many aftermarket programmers that can read the codes.

In any event, we recommend changing the fuel filter as a first step in troubleshooting just about any engine running problem. The possibility exists that you can pick up a bad tank of fuel at any time.

MP

[CHVYMAN#9]

Injector hanging open. Do you see lots of smoke when this happens? How about noise like "ping" or hard fuel knock?

[carl]

I just went thru this with my 04 cc and the dealer found wires rubbing on the alt bracket gm has a bulletin out on this problem, good luck

[DmaxMaverick]

Originally posted by CHVYMAN#9:
Injector hanging open. Do you see lots of smoke when this happens? How about noise like "ping" or hard fuel knock? All 8 of mine were replaced for this very reason. The problem never "fixed itself", or got better, just worse. Smoke and heavy fuel knock. Never once did the SES light up.

It doesn't sound like Dougm is experiencing this.