The California Air Resources Board and U.S. Environmental Protection Agency Friday announced approval of an emissions modification for a limited number of the Volkswagen 2.0 liter diesel vehicles with a so-called defeat device. The vehicles eligible for this modification are referred to as “Generation 3” and appeared for a single year only, in model year 2015.

In September 2015, Volkswagen representatives admitted to CARB and U.S. EPA the presence of a defeat device in 2.0 liter diesel passenger vehicles sold in model years 2009-2015. This device, in the form of a set of software commands, engaged the car’s emissions control system to deliver legal levels of nitrogen oxide (NOx) when the car was being tested for emissions in the laboratory. Once on the open road and out of the lab, however, the defeat device compromised operation of the emissions control system resulting in excess emissions of NOx at levels well beyond legal limits. Volkswagen sold approximately a half-million of the affected diesel vehicles in the U.S. including about 71,000 in California. This modification applies to more than 10,000 of= those cars in California.

“This is one more step on the road to cleaning up the mess created by Volkswagen’s deception, but it is by no means the last step,” said CARB Chair Mary D. Nichols. “There are more modifications to come for other model years, and further penalties to be decided.”

Because of the presence of the defeat device, these vehicles emitted up to 40 times the NOx allowed under their certification requirements. NOx emissions contribute to the formation of ozone, and can worsen symptoms of asthma and cardio-pulmonary disease. About 10 million Californians live in what U.S. EPA considers severe non-attainment areas for ozone. Volkswagen is paying more than $1.2 billion to the State of California to mitigate past excess NOx emissions of all 2.0 liter diesel cars, including any future emissions these cars may produce.

A partial consent decree approved by a federal judge in October http://www.cand.uscourts.gov/filelibrary/1776/Partial-Consent-Decree.pdf contains about 60 pages of detailed standards, requirements and criteria (known as Appendix B) in order for a proposed modification of these vehicles to be accepted.

There are several different generations of engine technology in these vehicles, depending on their age. The current accepted modification is for 2015 “Generation 3” models only and involves the installation of a second NOx sensor and a new or replacement diesel oxidation catalyst. This modification will reduce excess emissions from the affected vehicles by 80 to 90 percent. Owners of the affected 2.0 liter diesel cars have the option of getting their vehicle modified or taking an offer from Volkswagen to buy back the vehicle. Lessees may cancel their leases without additional cost or penalty. Volkswagen must notify owners of vehicles eligible for modification within 10 days of this announcement.

U.S. EPA’s statement and other information is here: https://www.epa.gov/vw/announcements-volkswagen-violations

CARB Modification FAQ is here: https://www.arb.ca.gov/msprog/vw_info/vw_faq.htm

Volkswagen page is here: https://www.vwdieselinfo.com/