The fire off the eastbound lanes near Santo Road was reported shortly before 4:30 p.m., according to the San Diego Fire-Rescue Department and the California Highway Patrol.
Fire officials said the cause of the blaze had not yet been determined.
One of the highway’s eastbound lanes was blocked and a SigAlert was issued, according to the CHP.
Authorities also called for the closure of the connector from Santo Road to eastbound state Route 52.
No injuries were reported, and no structures were threatened, fire officials said. Mission Trails Regional Park was closed, a SDFRD dispatcher said.