Diesel Drivers: Understanding Ad Blue for a better driving experience

Written by Cian Ryan

4 mins read

What is Ad Blue, and why do I need it?

In simple terms, Ad Blue is a synthetic urea and water-based additive which is injected into your diesel vehicle’s exhaust system to reduce harmful emissions, making it a pretty important element of the vehicle.

How does it work, and what do I need to know?

Your vehicle’s Ad Blue system is quite simple in principle, but due to its corrosive nature, it is open to causing issues for our drivers if misused.

Ad Blue is stored in an isolated tank, separate from your fuel system and any part of your engine. The fluid is injected directly into your Selective Reduction Catalyst (SCR), where it is then mixed with your exhaust fumes. The Ad Blue is a catalyst to convert Oxides of Nitrogen (NOx) into nitrogen, water and trace amounts of CO2. Pretty cool science!

NOx gases are a key contributor to the negative effects on respiratory health, and are generally attributed to diesel vehicle emissions based on the extremely high combustion temperatures and pressures found inside modern diesel engines. Various efforts are taken to reduce excessive temperatures, and Ad Blue injection to the SCR is the final critical step in treating spent gasses in an effort to protect human health.

The potential downside of Ad Blue

No system is perfect, but often the human factor involved can create a problem if mistakes are made. While we do see mechanical breakdown of components in the Ad Blue system, the leading and most costly area of concern is an Ad Blue mis-fuel, that is to say, when Ad Blue is accidently inserted into the fuel system, leading to potentially dire consequences for the vehicle.

As stated, Ad Blue is highly corrosive and if you’ve ever spilled some on the ground, you may have noticed that when exposed to air it will form fine crystalline structures. The issue here is that modern diesel fuel systems are built to incredibly fine tolerance levels, where even the slightest contaminant can cause serious damage. Unlike a petrol mis-fuel, simply draining and cleaning the fuel system is rarely enough to remedy the problem in diesel vehicles, and is no longer the industry standard. With time, we have learned that even after a flush, trace amounts of Ad Blue can damage pipe connections, fuel injectors, high pressure fuel pumps, and more, all of which are likely to fail after months of seemingly reliable driving.

The new standard is to replace the entire fuel system, from the filler tube to the fuel injector, once Ad Blue has been mistakenly placed into the fuel system. An expensive repair which can be avoided with a little carefulness on behalf of the driver.

In summary

Ad Blue is a key component for engineers to employ when designing modern diesel engines, and due to EU legislation, we are unlikely to see it removed from vehicles in the future. In Ireland, it is also illegal to modify or interfere with emission reduction systems. So our best option to ensure that the vehicles, and associated parts, are being maintained and repaired to the highest standard.

As noted, the most common issue we have encountered are mis-fuelling errors when driver’s attempt to refill their Ad Blue tanks. The easiest way to negate this issue and protect your company from the costs associated with this repair is to have your Ad Blue filled by a trained professional in one of our nominated suppliers, be that a main dealer, or BestDrive between services.

If you have any other questions in relation to your vehicles emission control system, or any concerns in relation to Ad Blue in general, please reach out to our Driver Support team today.

Our Diesel drivers might also be interested in our article on “The importance of maintaining your Diesel Particulate Filter”

Cian Ryan is Maintenance & Technical advisor at NiftiBusiness. With over a decade of motor industry experience, Cian is responsible for all technical queries and major repairs related to our fleet.

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