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AdBlue (Diesel Exhaust Fluid)

Does your vehicle require Diesel Exhaust Fluid (DEF)? Do you know what AdBlue is? Do you know when to top it up? 

Applied Leasing have put together a short guide to answer all your questions.

What is Diesel Exhaust Fluid (DEF)?

When diesel engines burn fuel, they pump a vast range of chemicals and pollutants into the atmosphere through the exhaust pipe; two of which are Nitrogen Oxide and Nitrogen Dioxide. These 2 chemicals are said to be responsible for acid rain, smog and respiratory problems in vulnerable people. DEF, otherwise known as AdBlue, is a non-flammable, high purity urea solution which is injected into the exhaust system just ahead of the catalytic converter. This odourless solution, combined with a hot exhaust system, releases ammonia which starts a chemical reaction that converts Nitrogen Oxide into harmless products - Nitrogen and water vapour.

Does my vehicle have DEF technology?

Due to the Euro6 emissions regulations more and more diesel vehicles are using DEF technology. If you are not sure if your vehicle uses it, then we advise you to check your manufacturer’s handbook.

When do I need to top up my AdBlue?

If your vehicle is fitted with DEF technology, it is vitally important that you keep the AdBlue fluid topped up regularly and according to the manufacturer’s guidelines. Low level warning lights will be visible on the vehicles display and must not be ignored.

How often will I need to top up?

AdBlue will be topped up at every service of your vehicle but the size of the tank varies from model to model. Smaller tanks will require additional top ups between services. There are other factors that affect the rate of consumption such as; mileage, journey types, driving style and environment. When the low-level warning light comes on it is time to top up.

What happens if I don’t top up?

If your vehicle runs out of AdBlue fluid it will go into limp mode and fail to start.

What is “limp mode”?

When AdBlue is low or empty the vehicle is no longer able to maintain the required emissions. This may cause the vehicle to fail its MOT. Some manufacturers have installed a failsafe which prevents the vehicle from starting when the AdBlue fluid has run out. This is to ensure that vehicles don’t drive illegally with high exhaust emissions.

Where can I buy AdBlue fluid?

You may have seen stock piles of AdBlue at your local filling station, but it is also available in most franchised dealers, online or from high street motor retailers like Halfords. You should always consult your manufacturer or handbook before topping up to limit any damage to the exhaust system. 

Note: Some manufacturers, like Jaguar, provide an extra top up service for AdBlue fluid.

How do I top up?

Topping up the DEF tank is as easy as topping up your diesel. The cap is often located near the diesel filler and most AdBlue is sold in handy containers with non-drip spouts. Your manufacturers handbook will be able to point you in the right direction – in more detail. 

Whilst AdBlue may be harmless to humans it can be corrosive to vehicle paintwork, upholstery, clothing and wiring, so extra caution is advised when topping up and storing your AdBlue fluid.

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