VW Diesel Scandal - Seeing Through the Noise and Smoke

Andy Y
September 24, 2015

Over the past week it has been hard to avoid the ongoing scandal surrounding Volkswagen’s attempts to circumvent EPA emissions tests. While the specifics warrant a full length book, here are the most relevant facts.

There are two fuels typically powering today’s vehicles, diesel and gasoline. Diesel fuel is much more energy dense than gasoline and can therefore provide superior fuel economy and torque. The downside to this increased fuel economy is that diesel engines emit more nitrogen oxide and carbon dioxide (NOx and CO2). Both of these contribute to the smog which affects air quality and the environment.

The U.S. market has consistently been a hard sell for diesel powered vehicles. The word “diesel” conjures up images of belching ferry boats, city busses, and your Econ professor’s old Benz. But in recent years new technologies have transformed the loud, smelly diesels of yesteryear into quiet, powerful, clean burning machines. These newer technologies combined with Increasing fuel costs have made the efficient diesel engine a more attractive option for consumers.

It was discovered that on particular models from 2009 to 2015, Volkswagen had installed complex software in some of their “clean diesel” vehicles. The Volkswagen Jetta, Beetle, Golf, Passat, and Audi A3 diesel models were included in Volkswagen’s eventual admittance to the EPA. There are nearly half a million affected vehicles in the United States, and 11 Million worldwide. This software recognized when the vehicle was undergoing an emissions test and the engine computer’s parameters were changed in order to meet the EPA’s emissions standards. An independent company stumbled upon this while testing vehicles in the real world, where the vehicles were found to emit up to 40 times the limit of nitrogen oxides, or NOx. While Volkswagen has yet to provide an explanation for why it disabled the emissions controls, industry analysts have speculated that the emissions controls hindered vehicle performance.

So what does this mean for consumers that currently own these vehicles? The EPA has ordered them to be fixed at Volkswagen’s expense, and Volkswagen has halted all new sales of affected vehicles. There is no immediate safety risk posed by the vehicles and they remain legal for the time being. While Volkswagen will likely issue a recall to remedy this issue, it is unclear how many consumers would choose to have it performed given that they would likely end up with less horsepower and poorer fuel economy than they currently enjoy.

Another issue facing current owners is that of diminished value. Currently the diesel versions of these vehicles sell at premium compared to their gasoline counterparts. Since any recall to fix the “defeat devices” would likely degrade performance, it is assumed the resale value of these vehicles would no longer reflect that premium. So far there has been at least one class action lawsuit filed against Volkswagen on behalf of consumers regarding fraud and diminished value. Check out to keep up with the latest news and information about your vehicle. In order to receive recall notifications about your vehicle, go to

Andy Y

About the Author

Andy Y is an automotive expert at RepairPal, the leading online source of auto repair resources and estimates. With many ASE Master certified mechanics on staff who have decades of experience, RepairPal knows all the fine points of car repair.

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By , November 28, 2015
I love diesel, but diesels really need to breath to obtain the best fuel economy potential and lowest soot particulate emissions. Most modern diesels are barely more efficient now than a modern direct injected gas turbo motor. Why? Because they cannot breath as they were intended too. Diesel fuel needs alot of oxygen to create a thorough and complete combustion event. For instance, just take a look at the Gale Banks Sidewinder-Duramax drag truck, a 7 second rocket that visually only emits tire smoke, yes he's using high amounts of nitrous and high turbo boost levels, but that just proves the point, more air equals a cleaner low soot combustion event. The emission expectations and mandates required to sell a modern diesel in the USA and Europe have caused the modern diesel engine to become a very expensive venture to purchase and maintain, and much less efficient than they potentially could be. Some common seen problems...Urea injection tank heaters and delivery nozzle failures, DPF issues, EGR related issues, faulty sensors, the list goes on. Basically the EPA want's the industry to contain all the particulate matter soot, store it in the DPF, then burn it out later by overheating it with more fuel, all while requiring low NOX levels. The demand on manufacturers to design a consistently stricter EPA compliant diesel engine is a huge engineering challenge to say the least. Here's how I see it and this is just my opinion, and as the saying goes, for every action there is a reaction, some positive and most negative depending on your perspective. EGR and diesel...this is really where the diesel emission controversy starts in my opinion...but first a basic lesson on what EGR is meant for. EGR is designed to reduce NOX gasses by keeping the initial combustion event inside the cylinder-s below 2500F. When the threshold goes above 2500F, NOX gasses increase dramatically, this holds true for both gasoline or diesel engines. In other words, EGR cools the initial combustion event by introducing an inert gas (a gas depleted of oxygen...exhaust gases) into the cylinder and acts as a filler mixing with the oxygen molecules and creates a cooler combustion event in hopes of getting it below the 2500F threshold for NOX reduction. EGR is great on clean burning gasoline engines as they emit very little soot particulates, the intake system stays relatively clean and you can actually benefit from increased fuel economy during cruise speeds due to the volumetric efficiency changes in cylinder air intake during active EGR, all while achieving NOX reduction. EGR and gasoline engines are a good match. Now lets look at EGR in a diesel. You introduce the EGR gasses into the intake and cylinder-s, now you just cooled the combustion event which in turn just caused "the particulate matter to increase" out the exhaust due to a cooler combustion event. These higher soot containing gasses are now going to be recycled back through the intake again at up to 35% while the rest gets trapped in the DPF exhaust filter. Although your NOX levels were decreased during this event, the cost is high in other areas of the engine. Anyone who works on diesel engines knows the intake tract carbon + soot contamination build up can be unimaginable on some engines, especially ones that do alot of stop and go driving. This also can cause DPF related issues as the engines need to complete more regeneration events in order to keep the DPF clean and the filter from clogging up. In a non EGR equipped diesel along with the cleaner ULSD 15ppm fuels, the intake stays clean as well as the cylinder head ports and intake valves as no EGR gasses are being introduced. The motor oil also stays very clean as well rivaling that of a gasoline engine. And mostly, the exhaust soot particulate matter is extremely low on a proper running engine. But the "NOX levels will be very high". You can't see these gasses, but they are there nonetheless. So which is worse? EGR or no EGR? That's the million dollar question, actually the billion dollar question. Even with high flow EGR, the NOX levels are in need of further suppression with a catalytic converter and Urea injection into the exhaust. The need for burning more fuel during a regeneration DPF clean out and having overall reduced fuel economy due to the high soot levels being trapped in the DPF. Is it really worth it? In other words, burn more fuel to clean the air because EGR caused higher soot levels clogging the DPF more frequently. Figure out a way to substantially reduce diesel NOX gasses without the need for EGR and you will be a hero, a very rich hero. I have heard talk of an inert gas generator to replace EGR as a clean inert gas that doesn't pollute the intake tract with soot, but that still leaves the high soot level particulate emissions from cooled combustion, but it's a good start. So what does this all have to do with Volkswagen? It really has to do with all diesel engine manufacturers, everyone will be watching what happens next to VW as it will very likely effect all future mandates and add yet more difficult challenges in trying to figure out how to meet the standards. One step already in place is we are seeing smaller displacement high output diesel engines being fitted in new models on some makes. The smaller engine is one way currently to meet new tier standards. Remember, these are just my thoughts, all comments are welcome. It just seems that our government is out to kill diesel by mandating unrealistic standards. HJ
By , December 08, 2015
So I own a 2013 Passat and a 2013 Jetta. I have not been able to drive my Passat for 3 months because it will barely run and the glow plug light came on and it acted like the turbo was not working. I finally got it to the dealership in McKinney Texas where I bought it from after receiving my notice that I will be receiving my Christmas bonus next week. Diagnostic will cost me $118.00. So after 4 hours I get the dreaded call from the VW service department. John proceeds to inform me that an air hose on the turbo was loose and evidently had been loose for a long time. Now it only has about 75 to 100 miles on the Passat since the flow plug light came on. So the loose air hose on the turbo has allowed the system to dump more fuel and less air in to the cylinder causing the black smoke. Excuse me ther has been no black smoke and now I know why the Passat uses 3 times more DEF blue than the Jetta. With the excess fuel and insufficient air it has cause extremely excessive soot in the exhaust system and the soot level is at 42 grams and the maximum acceptable level is 35 grams. All of the codes indicated that the loose hose caused all the emission problems which includes the Exhaust Heat Sensor, Exhaust Sensors, and other parts and labor for cleaning and replacing all the parts at a cost of $3,600.00. I am sorry but my Christmas bonus will not cover half of the cost to repair. Million dollar question is so I get it home and continue to make payments on something that does not work or do I just leave it at the dealership for VW Credit to keep their piece of junk???? I believe the dealership is not being truthful about a loose hose so I believe I will bring it home after paying the $118.00 diagnostic and find an attorney. It just seems funny that the entire emission system which has an issue and there will be a recall sooner or later for an issue that is caused by VW deceptive software and a loose hose can cause the same problem. Key thing is warranty and or recall does not cover a loose hose. Russell A. Turner
By , December 31, 2015
I think that these problems should be taken care of by the manufacture, They are the ones that should be responsible. I just purchased a 2011 Jetta, not even three days later it started cutting off, when I drive for 10miles or more and stop at a red light it would cut off, or driving around town is out of the question, it would start back up after it seems like I would let it sit for several hours, what's up with that, I've returned it to the dealer, and their sending it to a volkswagon specialist. I hope that they can fix the problem because money doesn't grow on trees and I'm tired of the bullshit.