As Ars Technica reports today, the CARB called VW's plan "substantially deficient" and that it "fall[s] far short" of the state regulator's standards. CARB also claims Volkswagen "failed to disclose and provide a complete description of all defeat devices" and accuses the company of being vague about how the fix will actually affect the vehicles' emissions, fuel economy, and On Board Diagnostics systems. According to a statement provided to Ars, however, the rejection is just "a procedural step under California state law."

It is worth noting that CARB initially rejected the 2.0L recall plan citing similar reasons. According to Volkswagen's attorneys, the defeat devices on the 3.0L vehicles are different and they initially believed those vehicles could be fixed without a full-scale buyback program.