Many modern motorhomes, being based on recent diesel vehicles, have an extra tank that surprises anyone unfamiliar with it: the AdBlue tank. Ignoring it can leave your vehicle unable to start at the worst possible moment, so it's worth knowing what it is and how to manage it. Here it is explained clearly and simply.
What AdBlue is
AdBlue is a fluid (a urea and water solution) used by modern diesel engines to reduce pollutant emissions (nitrogen oxides) in the exhaust system (SCR). It isn't a fuel additive: it goes in its own separate tank from the diesel, and the engine gradually uses it up.
The important part: don't run out
Here's the key point that catches many people out: if you run out of AdBlue, the vehicle may fail to start. Under emissions regulations, when the tank runs low, the vehicle first warns you well in advance ("top up AdBlue within X km" messages) and, if you ignore it until it runs out, it goes into a mode that prevents the engine from restarting until you refill it. It isn't a fault: it's designed to work that way. So don't ignore the warnings.
How to manage it
- Heed the dashboard warnings: they give you plenty of margin (hundreds of km); don't wait until the last moment.
- Top it up yourself: it's sold at petrol stations and shops (canisters with a spout, or pumps). It's easy to add through its filler cap (usually blue).
- Carry a spare canister on long trips or in remote areas, just in case.
- Consumption depends on the engine and driving style, but it's low; a tank lasts several thousand km.
- Be careful when handling it: never pour it into the diesel tank (a serious mistake!) and clean up any spills (it crystallises).
In summary
AdBlue is a fluid in a separate tank that reduces emissions in modern diesel engines, and the critical point is not to run out of it, because then the vehicle won't start. The step to take today: find your camper's AdBlue cap (usually blue), heed the dashboard warnings by topping up in good time, and carry a spare canister on long trips; that way it will never leave you stranded.