The check engine light is on when the engine computer has detected a malfunction and set a code. There are pages of possible causes. You need to have the system checked with a scan tool or code reader to have a starting point.
The 2004 GMC Sierra-1500 has a V6 engine.
The 2004 Chevrolet Silverado-1500 has a V6 engine.
The codes are read with an OBD2 scanner.
The 2004 Chevrolet Silverado-1500 has a 4.3 L base engine size.
The 2004 GMC Sierra-1500 has a 4.3 L base engine size.
A 2004 Ram 1500 has a 45rfe transmission.
Not all 2004 RAM 1500 models equipped with the Hemi engine have the Multi-Displacement System (MDS). The MDS feature was introduced in the 2005 model year for the 5.7L Hemi engine, allowing the engine to deactivate four cylinders under light-load conditions to improve fuel efficiency. Therefore, if you have a 2004 RAM 1500 Hemi, it will not have MDS.
The 2004 GMC Sierra-1500's engine produces 195 hp @ 4600 rpm.
The 2004 Chevrolet Silverado-1500's engine produces 195 hp @ 4600 rpm.
Have vehicle scanned to determine problem
The 2004 Chevrolet Silverado-1500's engine produces 260 ft-lbs. @ 2800 rpm.
The 2004 GMC Sierra-1500's engine produces 260 ft-lbs. @ 2800 rpm.