One problem related to brakes failed has been reported for the 2004 Hyundai Elantra. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Hyundai Elantra based on all problems reported for the 2004 Elantra.
Traveling southbound on interstate 5. Accident occurred in front of me requiring sudden application of brakes (panic stop). Brakes failed completely. The brakes worked partially after swerving and pumping the brakes. It was also found that the brakes had failed completely upon backing the vehicle. A mechanical inspection determined that the engine-booster vacuum line check valve had failed.