One problem related to o2 sensor has been reported for the 2004 Chevrolet Silverado 2500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Chevrolet Silverado 2500 based on all problems reported for the 2004 Silverado 2500.
Check engine light came on and "low engine power" flashed where the odometer is. This caused the rpm's not to go over 2800. Code reader claims O2 sensors or throttle control module or catalytic convertor issues. We discovered it was none of the above. To fix problem change 3 relays located under hood in fuse box. Relay #8864. Then clear codes, should fix issue unless code persists. Relays will cause a fire if not changed out ASAP.