One problem related to loud engine noise has been reported for the 2004 Chevrolet Trailblazer. The most recently reported issues are listed below.
The contact owns a 2004 Chevrolet Trailblazer. The contact started the ignition and suddenly, there was a loud noise outside of the vehicle. The vehicle was taken to an authorized dealer for diagnostic testing. The failure was contributed to the secondary air injection system. The contact repaired the vehicle. The component failed three months after the vehicle was repaired. The vehicle has not been repaired at this time. The VIN was unavailable. The failure mileage was 100.