Dykstra, 48, was arrested Thursday night by Los Angeles police at his Encino home on suspicion of trying to buy a stolen car, police spokesman Officer Christopher No said. He did not have other details.
Dykstra remained jailed Friday.
His arrest came a day after Dykstra, in an unrelated federal complaint, was charged with embezzling from a bankruptcy estate. He faces up to five years in federal prison if convicted.
Dykstra, who bought a Ventura County mansion once owned by hockey star Wayne Gretzky, filed for bankruptcy in 2009, claiming that he owed more than $31 million and had only $50,000 in assets.
Federal prosecutors contend that after filing, Dykstra hid, sold or destroyed more than $400,000 worth of items from the $18.5 million mansion without permission of a bankruptcy trustee.
The items allegedly ranged from sports memorabilia to a $50,000 sink. At one point, he sold "a truckload of furnishing and fixtures" for cash at a consignment store, according to a statement from the U.S. attorney's office.
It was not immediately clear whether Dykstra had obtained an attorney, U.S. attorney's office spokesman Thom Mrozek said.
Dykstra spent 12 years in the big leagues and helped the Mets to the World Series championship in 1986. He was a three-time All-Star in the 1990s while with the Phillies. He had the nickname "Nails" and was known for his rowdy behavior on and off the field.
In 2007, the Mitchell Report on steroid use in pro baseball mentioned allegations that Dykstra had used steroids. Dykstra has denied using performance-enhancing drugs.
After retiring, Dykstra had a number of business ventures, including owning a car wash, and wrote a stock-picking column on TheStreet.com, a financial website founded by TV host Jim Cramer.
However, he also was the subject of a number of lawsuits.
In January, his housekeeper alleged that Dykstra forced her to provide sexual favors but he denied the allegations and Los Angeles County prosecutors declined to file criminal charges.