California Highway Patrol says an unknown mechanical issue is the likely cause of the fire.
It started around 7 AM after the driver of the RV heard some popping sounds and pulled onto the right-hand shoulder of the highway, between the Avila Beach Drive and San Luis Bay Drive off-ramps.
He was looking into the cause of the sounds when the fire started.
The incident delayed traffic on the highway through Pismo Beach.
One non-injury accident was reported in the area of Highway 101 and Price Street.
Commutes were delayed for a few minutes, but some travelers reported traffic was backed up all the way to Arroyo Grande until 8 AM.
He was not injured, and the damages to the RV are extensive.