The suspicious object was spotted in an abandoned Audi sedan just off the freeway around 12:15 a.m.
The investigation prompted the closure of all freeway lanes in both directions as the bomb squad responded and removed the object with a remote control robot.
The suspected pipe bomb was then blown up in the freeway median and rendered safe.
Authorities said the suspicious object was just a pipe. It turned out to contain no explosives.
All lanes of the 605 Freeway were reopened in both directions around 2 a.m.