One problem related to engine shut off without warning has been reported for the 2004 GMC Sierra 1500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 GMC Sierra 1500 based on all problems reported for the 2004 Sierra 1500.
Reduced engine power, this has happened about 7 times. When this happens the engine shuts down to 1500 rpms maximum. Took to dealer, they told me that it was the throttle body valve and actuator assembly. This part was replaced at a cost of $481. Within two weeks the same problem has happened twice more. This is dangerous when traveling in traffic.