Legal Question in Real Estate Law in California

Technically, yes, the seller is still responsible. If you are the buyer, whether you'll be able to get the seller to pay up will be another matter! There is always small claims court, where you can file a lawsuit without an attorney on this type of matter for up to $10,000.

From the Bureau of Automotive Repair website:

"When a used vehicle is sold in California, the seller is legally responsible for making sure that the vehicle's emission (smog) control equipment complies with state requirements. There is no provision in the law allowing a seller to sell a vehicle "as is." The buyer must submit the certificate of compliance (smog certificate) to the Department of Motor Vehicles (DMV) when transferring registration of the vehicle. Without the smog certificate, the transfer of ownership cannot be completed.

Who pays for the Smog Check?

In private party transactions, the seller must provide the buyer with a proof of smog certification prior to the transfer of ownership. If the vehicle is purchased from a dealer, the passing Vehicle Inspection Report should be provided as part of the transfer documents. It is evidence that the vehicle meets state requirements for smog equipment. A vehicle that has not been issued a smog certification cannot be registered."