Volkswagen and Audi executives will meet with U.S. environmental regulators this week, ahead of a Nov. 20 deadline to submit a plan to fix nearly 500,000 diesel cars that violate pollution emission rules, people familiar with the matter said.

Friedrich Eichler, VW’s powertrain development chief, is scheduled to meet with the Environmental Protection Agency and the California Air Resources Board (CARB) later this week to discuss the company’s efforts to fix 482,000 diesel cars that do not comply with government emissions standards, the people said.

A separate U.S. meeting is planned with senior Audi officials, the people said, asking not to be named because the meetings are not public, according to Reuters.

Hans-Gerd Bode, a VW spokesman in Germany, declined to confirm the planned U.S. meetings, but said Friday that Eichler had held previous meetings with U.S. regulators and “he is not the only one (from VW) who is participating” in meetings.

EPA declined to discuss who would attend the meetings.

“We are in frequent, ongoing discussions with VW about next steps,” EPA spokeswoman Laura Allen said Friday.

In early October, California said it had given VW until Nov. 20 to come up with a plan to fix the vehicles. While declining to discuss the meetings, CARB spokesman Dave Clegern said: “We’re trying to determine what a fix will look like and what else should be done, so we need to be able to communicate with people in confidence.”

U.S. regulators are urging VW to make progress in coming up with fixes for the vehicles sold since 2009, and also detailed plans for the newest models and 2016 cars that can’t be sold until VW can show the government aren’t in violation of emissions rules.

Last week, VW said it halted production of diesel 2016 Passat cars in Chattanooga, Tennessee, while awaiting a fix.

VW still has not proposed a specific fix for any of the three generations of diesel vehicles. EPA has said it must test any fix first before it will approve it.

“We discussed several options for those cars and engines which are affected,” VW spokesman Bode said.

VW admitted in September to installing the “defeat devices” in a meeting with EPA and CARB, halted sales 2015 models in showrooms and has withdrawn its request for government certification of 2016 diesel cars with 2.0 liter engines pending further talks.