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30 January 2026 (updated) How do I add AdBlue® to my car and how much of it do I put in?
AdBlue® is a registered trademark of the VDA Verband der Automobilindustrie e.V. (German Association of the Automotive Industry).
As modern diesel engines are designed to meet strict emissions standards, AdBlue® – a diesel exhaust fluid (DEF) – has become a key part of reducing harmful nitrogen oxide (NOx) emissions. The catalytic converter alone is no longer enough for meeting environmental goals.
If your vehicle uses Selective Catalytic Reduction (SCR) technology, you’ll need to refill AdBlue® regularly to ensure your engine runs properly and legally.In this guide, we’ll explain what this fluid is, how to refill it safely, how much to add, and what to do if problems arise.
What is AdBlue®?
AdBlue® is a non-toxic, transparent solution made of 32.5% high-purity urea and 67.5% deionised water. It is used in diesel vehicles equipped with SCR systems to break down harmful nitrogen oxide emissions into nitrogen and water vapour, making the exhaust gases more environmentally friendly.
How do I know if my car needs AdBlue®?
Not all diesel engines use AdBlue®, but many diesel models manufactured after 2014 do require it. This is due to manufacturers’ rapid adoption of SCR technology in order to meet modern EU emission requirements.
You can easily check whether your car uses it by referring to the car owner’s manual. The system is typically identified by its warning light on the dashboard or a bright blue filler cap near to the diesel tank.
How to refill AdBlue® in your car
Refilling AdBlue® is simple if you follow these step-by-step instructions:
- Locate the AdBlue® filler cap. It may be near the diesel filler neck (usually blue) or in the boot, under the bonnet, or in the spare wheel well, depending on the model.
- Remove the cap. Some makes, such as Audi, include special tools for opening the cap
- Turn off the engine and allow it to cool before refilling.
- Use a special AdBlue® refill bottle or funnel to avoid contamination.
- Pour slowly to avoid overfilling or spillage. Stop once the tank level reaches the required amount – most vehicles have sensors to alert you when it's enough.
- Tightly close the cap and wash away any spilled liquid with water.
- Start the engine. The warning light may take a few minutes to reset.
Always consult your owner’s manual or the manufacturer’s website for model-specific guidance. To find compatible diesel products online, make sure to specify the exact make and model (incl. the year) as well as the product category, e.g. “Ford Kuga DPF filter”.
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How much AdBlue® should I add?
AdBlue® consumption varies depending on the driving conditions and vehicle type, but here are general guidelines to consider:
- Most cars consume around 1 litre every 600 to 1,000 miles.
- A typical AdBlue® tank holds between 10 and 20 litres.
- Fill up when the dashboard AdBlue® warning light comes on. Don’t ignore it, as some cars may not start at all if the AdBlue® tank is empty.
Best way to store AdBlue®
Store AdBlue® in a sealed container in a cool, dry place (–5 °C to 25 °C), away from sunlight, and use it within 12–18 months to to maintain its effectiveness.
What to do if the AdBlue® warning light stays on
If the warning remains lit after refilling:
- Double-check that the cap is tightly sealed.
- Start the engine and leave it running for a few minutes to allow the system to detect the refill.
- If the light won’t turn off, contact your mechanic or dealership, as the system may need to be reset manually or checked for faults.
What happens if I put diesel in the AdBlue® tank?
If you accidentally pour diesel into the tank, it can contaminate the fluid and potentially damage components of the system, including the pump, injectors, and catalyst.
This can lead to costly repairs if not treated immediately. Take extra care when filling up, otherwise you may have to think about the price of a new catalytic converter and SCR system.
FAQs
Can I use water instead of AdBlue®?
No. Only certified AdBlue® should be used. Using water or substitutes can damage the SCR system and void your warranty.
Is AdBlue® the same for all diesel vehicles?
Yes, AdBlue® is a standardised fluid that meets ISO 22241 specifications and can be used in all compatible SCR systems.
Can I top up AdBlue® myself?
Yes, it's designed for user refilling. Just follow the safety guidelines and instructions in this article.
How often do I need to refill AdBlue®?
It depends on your driving habits and car model. On average, every 5,000 to 10,000 miles or when the warning light comes on.
How do I fill up the AdBlue® at a petrol station?
You can find AdBlue® filling stations and canisters at most well-known petrol stations in the UK, particularly those with HGV lanes. The pumps work in a similar way to fuel pumps. However, for most normal passenger vehicles, portable containers will do the job. You can find more competitive AdBlue® prices online.
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