The California Air Resources Board has rejected Volkswagen's plan to fix the 3.0L TDI V6.
"VW's and Audi's submissions are incomplete, substantially deficient, and fall far short of meeting the legal requirements to return these vehicles to the claimed certified configuration," CARB wrote in a letter to the German automaker.
This comes as a bit of a surprise as last month, Volkswagen's lawyer Robert Giuffra said the company was close to a fix for this engine and it wouldn't affect overall performance.
Volkswagen apparently did not learn its lesson when its proposed fix for the 2.0L TDI four-cylinder was rejected by CARB earlier this year for the same reasons.
Complicating matters further is CARB saying that certain test data would not be available until December. They need this data to help make a determination if a fix would work for the all of the affected models or if Volkswagen needs to set up a buyback program similar to the one for the 2.0 TDI.