One problem related to diesel engine has been reported for the 2001 GMC Sierra. The most recently reported issues are listed below.
When the air conditioner (a/c) is used it takes at least eight minutes for the cool air to flow. There is a foul odor coming from the vents that smells like rotten eggs. Also, consumer is concerned with the sound of the engine. Although the vehicle is equipped with a gas engine, it sounds like a diesel engine. There is a irritating noise that occurs intermittently at any speed. The dealer claims that the noise is normal. Engine burns 3 qts. Of oil every 3000 miles and the fuel gauge isn't accurate.