The US Environmental Protection Agency (EPA) also notified automakers that it may test or require testing on any vehicle at a designated location, using driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use, for the purposes of investigating a potential defeat device. Such testing can be expected in addition to the standard emissions test cycles when Emissions Data Vehicles (EDV), and Fuel Economy Data Vehicles (FEDV) are tested by EPA.

ARB and the EPA were alerted to emissions problems with the Volkswagen vehicles in May 2014. For a year following, VW asserted that the increased emissions could be attributed to various technical issues and unexpected in-use conditions. VW then issued a voluntary recall in December 2014 to deal with the issue. ARB, coordinating with EPA, conducted follow-up testing, which found only a limited benefit from the recall.

ARB then broadened the investigation to determine the technical nature of the poor emissions performance and to figure out why the onboard diagnostics were not detecting the problem. Among its tests, ARB developed a special dynamometer cycle, and used OBD (on-board diagnostics) interrogation and PEMS (Portable Emissions Measurement Systems) measurements. ARB will use this same suite of screening techniques in its testing of the diesel engines.

In the letter, Annette Hebert, Chief, Emissions Compliance, Automotive Regulations and Science Division, warns the manufacturers:

Beginning immediately, ARB will begin to utilize recently developed screening tests, which are based on ARB’s original work for assessing performance of modern light duty diesel engines, in ARB’s In-Use Compliance Program for non-approved AECD [auxiliary emission control device] and defeat device identification. The AECD and defeat device screening tests will be based on ARB’s newly-developed detection methods, and may include onboard diagnostic system interrogation, and/or the use of special driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use. This new screening testing approach shall be in addition to the standard certification emissions test cycles.

In the event that a suspected, non-approved AECD or defeat device is discovered through the use of the screening tests, the manufacturer will be notified, and will be expected to deliver production, or procure in-use, vehicles for additional in-use compliance evaluation by ARB at the manufacturer’s expense… In addition, ARB may require remedial measures to be taken at the manufacturer’s expense, and the manufacturer may be subject to penalties, as allowed by law. As always, if there are any other violations ARB regulations discovered, ARB will take appropriate action, as allowed by law.

In addition, ARB made the following statement regarding actions related to cars with diesel engines manufactured by Volkswagen.

The California Air Resources Board (CARB) and the United States Environmental Protection Agency (USEPA) are working with Volkswagen to evaluate potential recall solutions for the affected vehicles. The September 18, 2015 CARB In-Use Compliance letter and USEPA Notice of Violation cover three generations of Volkswagen four-cylinder diesel vehicles.

Both CARB and USEPA will evaluate the technical solutions that Volkswagen develops to ensure their emissions performance is corrected back or close to expected levels in real world driving. Recall actions proposed by Volkswagen will also be scrutinized for any potential adverse impacts on consumers. As both agencies and Volkswagen get closer to final recall solutions, those solutions will be communicated to consumers through the media and more formally by Volkswagen through recall action letters to affected vehicle owners.

CARB will take actions that protect public health, air quality and consumers by aggressively continuing its ongoing investigation into Volkswagen’s defeat device, with additional testing and investigation of the potential presence of similar devices in vehicles across manufacturers.