Diesel Emissions Tests Faked, but How Did They Do It and Why?

Ian Lewis[1]

Ian Lewis

Money Savings Advice Diesel emissions tests faked

In what came to be known as Dieselgate, it was discovered that car manufacturers had faked diesel emissions test results. Many cars passed emissions tests despite producing too much nitrogen oxide.

A car’s diesel emissions need to be below a limit set by the country it’s sold in. Cars go through emissions testing to make sure that they’re reasonably safe. In 2014, it was found that car manufacturers had been manipulating test results. U

sing defeat devices, they’d faked the results of diesel emissions tests.

Read on to find out more about Dieselgate, and the cars that were part of a huge diesel emissions scandal.

Looking for other information on the Diesel Emissions scandal or compensation claims ? This guide has info on 'Diesel emission test faked, but how?'. We have also writen extensively about:

We update all our guides regularly. If you are researching the Diesel Emissions scandal or compensation and we haven't got an exact guide that helps you, keep coming back as we update daily.

What Are Diesel Emissions, and Why Do They Matter?

A diesel car produces nitrogen oxide during fuel combustion. This toxic chemical has been responsible for damage to people and the planet. Nitrogen oxide is a greenhouse gas, able to break down the ozone layer. It’s also been found to cause problems with the eyes, damage lungs and contribute to cancer rates.

Nitrogen oxide levels in the air must be carefully controlled. If the levels are too high, these diesel emissions can lead to premature death. Emissions tests are used to make sure that cars aren’t producing too much nitrogen oxide.

In the UK and Europe, nitrogen oxide emissions must not rise above 0.080g/km.

Why Were Emissions Tests Faked?

Keeping diesel emissions low isn’t easy for car manufacturers. It’s a costly process and can have an influence on a vehicle’s performance.

Car manufacturers want to make vehicles that perform well and are cost-effective. Buyers look for powerful cars with great fuel economy, and they don’t want the hassle of extra servicing to maintain filters and keep emissions low. They also want cars that don’t cost too much at first, which is a challenge for the people that are making cars.

Consumers expect a lot for their money. Manufacturers want to make their profit. Something had to give, and manufacturers responded by cheating emissions tests worldwide.

Manufacturers worked out that they could maintain performance and keep fuel economy high, by only using their best diesel emissions filter tech for a short while. These filters could be active during test conditions, but not during real-world driving. Consumers wouldn’t know the difference, and the cars could pass diesel emissions tests.

How Were Diesel Emissions Test Results Faked?

Car manufacturers had been putting defeat devices in their vehicles. These pieces of software temporarily changed how their cars would behave. In test conditions, for example, when a car was running at a very low speed, diesel emissions could be reduced so a car would get through an emissions test. Once the car was out in real driving conditions, the diesel emissions were much higher.

Manufacturers knew how the diesel emissions tests worked, and what was involved. For example, where tests were done over 15 miles, they could use a defeat device until the 16th mile of any trip. In this way, diesel emissions were falsely recorded as much lower than they really were.

How Were Faked Diesel Emissions Tests Discovered?

In 2013, the International Council on Clean Transportation was commissioned to carry out research. They started with Volkswagen vehicles, purely by chance. Their research involved checking the emissions of diesel cars driving on roads. Researchers found that many cars were producing too much nitrogen oxide.

In some cases, nitrogen oxide levels were up to 40% higher than recorded under test conditions. It was clear to researchers that this wasn’t an accident, but deliberate use of defeat devices to circumvent the tests.

Before they released their findings, researchers ran tests on more vehicles in more environments. They found a widespread problem, with several manufacturers equipping their cars with these defeat devices. This meant that a significant proportion of diesel cars should not have been on the roads.

Even after releasing reports that told consumers that they’d been lied to, researchers found that behaviour didn’t change straight away. Some manufacturers continued to sell cars with defeat devices installed, whilst others recalled vehicles only to make defeat devices even more efficient.

Even now, many millions of cars are on the road with emission levels higher than the recommended limits, contributing to the global pollution crisis and risking public health.

Could Emissions Test Results Be Faked Again?

Those in charge of diesel emissions tests have had to learn some big lessons. Tests are now carried out in wider conditions, including more real-world driving. It’d be much harder for car manufacturers to manipulate tests and cheat the system.

Defeat devices work by identifying when a car’s under test conditions. They’re only active when a car’s being tested, but don’t work during everyday driving. By putting everyday driving conditions into their diesel emissions tests, those in charge of testing emissions can reduce the risk of any fake results.

Also, many major manufacturers are facing heavy fines and multiple court cases. Even if they could fake the results again, they would probably decide against it, as the financial savings they would otherwise make would be wiped out with court costs and other punishments.

Was Your Car Affected?

Many diesel cars were affected by the diesel emissions test scandal. You can find out if yours has been recalled if you know your car’s VIN. Search online for ‘diesel emissions recall’ followed by the name of the car manufacturer. If your car might have been recalled, you can search with your VIN or car registration.

If your car has been recalled, it’ll need to go to an approved workshop. Modifications to your car will improve its diesel emissions. Any defeat devices should be deactivated. You may notice minor changes to your car’s fuel economy or its performance. You should also make sure you check whenever you’re about to buy a second-hand diesel car, so you know whether the repair work has been carried out.

The costs of adjustments will be covered by the car manufacturer. They’ll make sure that diesel emissions now fall within legal limits.

Can You Claim Compensation for Faked Diesel Emissions?

If your car was part of the diesel emissions scandal, then you might be able to claim compensation and get back a proportion of the purchase price. For most people, compensation will be anything from 25% to 100% of the vehicle value.

Car manufacturers have already had to pay fines and penalties for their behaviour. These include $4.3 billion paid by Volkswagen and 870 million euros by Mercedes-Benz. On top of these corporate fines, manufacturers must act to make things right for the consumers that have been affected.

The best way to claim compensation is to get involved in group action. Legal firms are offering to represent groups of diesel car owners. Group action removes the pressure from individuals, providing strength in numbers and increasing your chance of success.

To find a law firm and claim compensation, it’s best to search online using ‘diesel compensation [car make]’. Your results will include several different law firms that are offering to represent car owners. You can make a claim with others like you, affected by fake diesel emissions test results that could have put their families at risk.

How Can Money Savings Advice Help You With Making a Compensation Claim?

Here at Money Savings Advice, we have partnered with some of the UK’s leading claims management companies. They have already helped thousands of people claim compensation, and they can do the same for you.

Choosing an independent claims management company means they won’t proceed with a claim unless they are sure it is in your best interests. They are also regulated by the FCA, which gives you an additional layer of protection.

If you would like to speak to one of these claim management companies who can help you make a compensation claim, then click on the below and answer the very simple questions.

Money Savings Advice Author Ian Lewis

Ian Lewis

Ian Lewis is one of our specialist financial writers. Ian has over 15 years of financial writing experience, having worked for some of the largest financial publications in the UK covering topics from mortgages, equity release, loans and financial claims, to name a few.

How does Money Savings Advice work

Money Savings Advice is an independent editorial company providing detailed information about numerous financial niches with the aim of helping consumers make informed financial decisions. We aim to provide hints, tips and techniques to help you make your money work for you. However, we are not perfect, and we accept no liability if anything we write about goes wrong.

  • The information detailed on Money Savings Advice does not constitute financial advice. It is always advised to do your own research to make sure the product/solution we write about fits your circumstances.
  • The aim of Money Savings Advice is to match you with a financial advisor, claims management company or another financial service company that can help you with your financial needs.
  • Money Savings Advice aim to provide the most up to date and accurate information about all financial subjects, and as such we sometimes link to other websites, but we (Money Savings Advice) can’t be responsible for their content.
  • Money Savings Advice is independent and not linked to any financial company.


Who are Money Savings Advice

Money Savings Advice is a trading name of RMM Digital Publishing Ltd. Registered trading address, First Floor, 85 Great Portland Street, London, W1W 7LT. Trading in England and Wales, company number 11550143 with data protection number ZA747669.

Back to top