Why do some Volkswagen diesels use AdBlue and others do not?

Why does Volkswagen use AdBlue for diesel engines in the Passat and Touareg, whereas the same engine used in Jetta does not require any AdBlue to run clean?

F.K., Ottawa, Canada

Volkswagen says it was an engineering decision to use a diesel exhaust fluid such as AdBlue on its larger, heavier diesel models such as the Passat and Touareg as the best way to meet emissions regulations for nitrogen oxides (NOx). Other manufacturers, such as Mercedes-Benz, also use diesel exhaust fluid (a mixture of urea and water) on vehicles with diesel engines.

2013_passat_tdi

On the compact Golf, Jetta and Beetle models with the 2.0-liter TDI diesel engine, Volkswagen says it is able to meet emissions regulations with a catalytic converter that reduces NOx.

With the Passat and Touareg TDI models, AdBlue is sprayed into the exhaust stream to control NOx and must be replenished periodically. Typically that is around every 10,000 miles, though it could run out sooner depending on temperatures and how the vehicle is driven. A warning light signals when the AdBlue tank is running low, and when the tank is empty, the car won’t start to comply with emissions regulations.

In the U.S., AdBlue refills are included in the three-year/36,000-mile free maintenance provided on new Volkswagens at 10,000, 20,000 and 30,000 miles. Volkswagen Canada does not provide the free maintenance perk, so it will come out of your pocket. In addition to VW dealers, diesel exhaust fluid should be available at repair shops and, if you’re a do-it-yourselfer, at auto parts stores.

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Answered by Rick Popely on November 13, 2012 in I'm Just Wondering , volkswagen | Permalink

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