Darlington: How Does AdBlue End Up in a Diesel Tank, and How Do You Avoid It?

AdBlue in a diesel vehicle: two tanks, two fillers

Diesel feeds the engine — yet plenty of current diesels seen around Darlington and Albert Hill carry another fluid as well. AdBlue goes to your exhaust, where it is sprayed into the gas to clean it, and it lives in a tank of its own.

Each tank has its own filler. Under one flap, side by side: that's the arrangement on many cars. Elsewhere, AdBlue's filler sits beneath the bonnet or in the boot instead. Diesel goes in on every forecourt visit, week in, week out. A driver who has to stop and think where it goes usually fills the AdBlue side, from a bottle, and far less regularly. That gap is where the error lives.

Telling the AdBlue filler from your diesel filler

Be it a Darlington forecourt or a drive out in Eastbourne, spend a few seconds on these before any goes in.

• The cap. The AdBlue cap is regularly blue, or marked "AdBlue". Your diesel cap normally is not. Read it rather than going by where it sits.
• On plenty of cars, the size tells: AdBlue has the smaller filler neck.
• Look inside your fuel flap: many motors have a label there showing which fuel goes where.
• The handbook. If the filler isn't by the diesel cap, it is in your boot or under the bonnet, and the handbook says which.
• Collecting a hire or company car, say at the car park outside the nearest station? Check with the person who drove it last before you set off, rather than once the light comes on.

What occurs when our technicians get there around Darlington

Outside St Augustine's Catholic Primary School, close to Resurgence or on your own driveway: wherever the car has stopped, we come to it. Those answers determine this work and the price, and so our technicians ask what went in, roughly how much, and if it has run. On the call itself, you hear our quote — before dispatch.

The fuel system is then flushed thoroughly, once the tank is emptied. AdBlue crystallises and is corrosive to some of the metals in a fuel system, and so it does not wash out on its own — which is why that matters more here than with petrol. A test comes at the end: before that, clean diesel is added, and the fuel filter is flushed or replaced as needed. After that we start it and make sure it runs correctly before we go.

Unrun cars usually need a half-hour job after the moment we arrive. The equipment is safe on a live forecourt, and hushed enough for a residential street late at night. Paying is on the day, not upfront, and you receive the paperwork an insurer asks for: an engineer's report and a VAT invoice. It's worth checking your insurance while we travel to you: misfuelling cover comes with plenty of policies.