California air quality regulators are rejecting Volkswagen's recall plan to fix vehicles including the Beetle and Jetta that were programmed to trick government emissions tests.
The California Air Resources Board said Tuesday that the plan did not meet its standards and was `unacceptable.'
The U.S. Environmental Protection Agency said it agrees with the move but is working on a different timetable.
Volkswagen says it continues to work with regulators.
The company's recall plan for 2.0-liter diesel engines covers 500,000 vehicles.
A recall plan for 85,000 3.0-liter engines is due next month.
Volkswagen told regulators last fall that it had installed software on its 2009 to 2015 diesel engine models to bypass government emissions tests