One problem related to brake light on has been reported for the 2003 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Hyundai Sonata based on all problems reported for the 2003 Sonata.
My neighbors informed me that my brake lights were stuck on. One of them researched and read that it may be the m48 stop lamp switch. We found the plastic backing portion from the contact plate that pushes the switch in. It was broken in pieces and laying on the floor mat below the brake pedal. He replaced it with something that is temporarily doing the job. I will be taking my car into the Hyundai dealer next week to have this fixed. They will also be replacing my gas tank that got punctured while they were replacing the valve-canister cl, canister assy. , and valve-purge contr. Back in Feb. 2014 when I could not easily get fuel into the vehicle. I believe the fuel issue should be a recall as well from all of the people I have seen on the internet searching for resolutions to the same problem with their Hyundai's.