Illegal Volkswagen diesel emission systems may require two solutions
By Paul Lienert and Joseph White
DETROIT (Reuters) - Volkswagen AG <VOWG_p.DE>'s promise to fix pollution control systems on about 11 million diesel vehicles will involve changes to software, and possibly hardware, that could leave owners with cars that deliver diminished fuel economy and performance or require more maintenance, experts said Tuesday.
The German automaker's new chief executive, Matthias Mueller, said Tuesday VW customers would need to have those diesel cars "refitted." The company did not specify what the refitting might entail. Some analysts have said the job could cost more than $6.5 billion.
A former executive of Volkswagen's U.S. operation said Tuesday the company may be required to change only software, and not hardware, to bring older diesel models now deemed illegal into compliance with U.S. emissions standards.
Other experts and U.S. regulators said the German automaker likely will have to come up with two sets of solutions for two different emission-control systems installed on 482,000 U.S. diesel cars from model years 2009-2015.
VW has admitted using software that circumvented U.S. and California pollution rules by fully activating the exhaust scrubbing systems only when the car was being put through precisely prescribed government emissions tests.
VW hasn't said why it used the illegal "defeat device" to deceive regulators. But the results, at least in the short term, were beneficial: VW was able to pass laboratory tests that showed its U.S. diesel cars met the relevant regulations, but then switched off the emission control devices while driving.
The benefits of switching the pollution control systems off were different depending on which system the vehicles used, experts said.
VW initially installed the illegal software, beginning in late 2008, on 2.0-liter four-cylinder turbo-diesel engines fitted with devices known as "lean NOx traps," designed to reduce nitrogen oxides in engine exhaust. Nitrogen oxide emissions have been linked to smog, acid rain and lung cancer.
EPA on September 25 said it would take longer to fix older VW diesels from model years 2009-2014 that used the lean NOx traps.
Any device used to control nitrogen oxide emissions typically "diminishes the performance and fuel economy" of diesel engines, according to automotive consultant Sandy Munro.
Older VW diesels could be made to function properly with a software fix, said Marc Trahan, who retired in late 2014 as executive vice president of group quality after a 35-year career with VW and its Audi subsidiary. They should not need to have newer hardware installed, which would take much longer, require extensive "re-engineering" and be cost-prohibitive, he said.
Beginning in 2012, Volkswagen offered the same 2.0 TDI engines with a more sophisticated and expensive emissions control system called Selective Catalytic Reduction. These systems, which debuted on VW's largest car, the Passat, injected a liquid urea solution into the exhaust to break down the nitrogen oxides.
These systems also had software that turned them off during normal driving, the company has admitted. The consequences of running the systems all the time will be different for consumers than the older, NOx traps.
Ideally, the urea solution used to control smog-forming gases is supposed to be replaced every 10,000 miles, typically by a dealer, but VW encountered potential problems.
On newer models with the SCR system, Trahan said there were concerns within the company about the urea consumption being so great that it would require separate "fill-ups" every 5,000 miles, rather than the desired 10,000-mile intervals that are typical between engine oil changes.
A software update on the newer diesel models equipped with SCR devices could lead to "reduced vehicle performance and fuel economy and increased urea use," said analyst Kevin Riddell of LMC Automotive. The new software "also will have an impact on resale value and potential marketability," he said.
(Additional reporting by Joseph White in Detroit. Editing by Joseph White and John Pickering)
