AdBlue Tips for Optimal Performance

AdBlue tips

Should you own or lease a modern Euro 6 diesel car, you may have to consider another important fluid. If you've ever wondered "What is AdBlue?", it is a diesel emissions fluid used to help modern vehicles reduce harmful exhaust gases and comply with emissions regulations.

Diesel Emission Fluid (known by its trade name, AdBlue) is mainly made from purified water and urea. Although harmless when used correctly, it can cause significant issues if handled incorrectly.

AdBlue at a glance

• Used in most Euro 6 diesel cars
• Injected into the exhaust system, not the engine
• Typical consumption is around 1 litre every 600 miles
• If the tank runs empty, your car may not restart
• Helps reduce harmful NOx emissions

What is the AdBlue system?

AdBlue fluid is a vital part of the car's Selective Catalytic Reduction (SCR) technology. The fluid is not injected into the engine but the exhaust system. This is performed automatically to reduce harmful NOx exhaust gases from polluting the air. Many cars will display an amber warning light on their fascias, should there be an issue, the meaning of which must be heeded, by consulting the owner's manual. These include top-up reminders.

How does the AdBlue system work?

When AdBlue is injected into the hot exhaust system, the heat present causes it to evaporate, leaving ammonia and carbon dioxide behind. As the exhaust gases flow into a catalytic converter within the exhaust system, the damaging NOx content reacts with the ammonia to form innocuous nitrogen and water.

How much AdBlue should I add?

Most drivers dose additional AdBlue, when warned by the AdBlue warning light on their dashboard. Typically, this gives plenty of warning with a mileage countdown. Some garages do so at service time, anyway.

The cost of AdBlue varies depending on where it is purchased. Filling stations with AdBlue pumps are often cheaper than buying smaller retail bottles.

When considering AdBlue consumption, driving technique plays a big part. The harder you drive, the more AdBlue is used. Typically, expect 1.0-litre to be consumed every 600 miles.

Can You Drive Without AdBlue?

Many drivers experiencing AdBlue problems ask whether they can continue driving without topping up the system.

While you may be able to continue driving temporarily after a warning appears, allowing the tank to run empty can cause significant issues:

• The vehicle may refuse to restart
• Dashboard warnings may remain active
• Diagnostic tools may be required
• Repair costs can increase

For this article, we shall consider issues that are caused by driver error, rather than those arising from wear and tear.

If you allow the AdBlue tank to run empty, the engine is unlikely to restart, even after you have refilled the tank. It may not be possible to reset the AdBlue warning afterwards without professional diagnostic equipment.

You will cause serious damage, by dosing AdBlue in the wrong place. Never add it to the fuel tank, cooling system, or oil sump. Be familiar with the AdBlue tank's location. Spillages are avoidable, by using a suitable bottle.

Never overfill the system, either. This situation can create a vacuum within the tank that prevents the AdBlue from being injected into the exhaust. Consequentially, the AdBlue light may remain illuminated after filling. The AdBlue pump and circuitry are located on top of the tank in some cars. Overfilling, therefore, risks moisture contamination that can damage the electrical system.

AdBlue and Cold Weather

AdBlue can freeze at approximately −11°C, which sometimes causes concern during winter conditions.

Modern vehicles are designed with heated tanks and delivery systems to prevent freezing from becoming a major issue. In most cases, the system will begin operating normally once temperatures increase.

However, repeated short journeys in cold conditions may contribute to some AdBlue problems, particularly if sensors or injectors are already deteriorating.

Does AdBlue Expire?

The AdBlue system cannot work correctly with out-of-date fluid, which has a finite shelf life. Never use AdBlue after the bottle's expiry date has passed and, unless you cover very high mileages, do not stockpile large quantities at home.

AdBlue has a finite shelf life and using out-of-date fluid can contribute to AdBlue problems and poor system performance.

Never use fluid after its expiry date and avoid storing large quantities unless you cover high annual mileage.

Ultra-violet light speeds up AdBlue’s deterioration and this can damage your exhaust system’s delicate Selective Catalytic Reduction catalyst. Therefore, buying bottles that have been sitting outside a petrol forecourt may not be a good idea. Instead, look for bottles that have been stored indoors, or in the dark.

AdBlue Crystallisation and How to Store It

AdBlue can crystallise when exposed to air or after spillages dry out. The white residue can clog components and potentially create performance issues.

To avoid crystallisation:

• Store bottles indoors and away from direct sunlight
• Keep containers sealed tightly
• Avoid contamination with fuel or water
• Clean spillages immediately
• Do not use old or damaged containers

Proper storage also helps avoid unnecessary cost of AdBlue increases caused by waste and system contamination.

Can I switch the AdBlue system off?

While some garages advertise AdBlue removal services, we advise against it. Anti-social implications aside, it results in you breaking the law. The UK government has useful information on this issue, should you be considering it.

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