A statement posted by Cheng's mother, "Mom J," on the website oneloveforchi.com said Cheng's heart stopped beating early Sunday.
"This is the hardest thing to write to you," she told Cheng's fans via the website. "Your love and heart and devotion to Chi was unconditional and amazing. I know that you will always remember him as a giant of a man on stage with a heart for every one of you.
"He was taken to the emergency room and at 3 a.m. today his heart just suddenly stopped. He left this world with me singing songs he liked in his ear."
Cheng was involved in a high-speed road collision in 2008 and was ejected from the vehicle, KROQ-FM, Pasadena, Calif., reported. He was not wearing a seat belt.
He had been in a semi conscious state since then.
A candlelight vigil has been scheduled for Sunday at 6:30 p.m. PDT in Sacramento's Cesar Chavez Park.