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

AdBlue in a diesel vehicle: two tanks, two fillers

No single fluid but two: that's how many newer diesels around Moss Bank and Simms Cross carry, with diesel feeding the engine. The exhaust, not the motor, is where AdBlue goes: sprayed into the gas to clean it, from a separate tank.

There is a filler on each tank. Under one flap, side by side: that is the arrangement on many cars. Elsewhere, AdBlue's filler is under the bonnet or in your boot instead. The diesel side is fuelled at the petrol pump all the time. Seldom filled, AdBlue normally comes out of a bottle, tipped by someone who must stop and think what cap to use. That gap is where the error lives.

Which filler is for AdBlue, and which for diesel?

A couple of seconds is all the checks take — so check them before you tip anything, on a drive in Crow Wood or a forecourt around Moss Bank.

• The cap. The AdBlue cap is regularly blue, or marked "AdBlue". The diesel cap usually is not. Read it instead of going by where it sits.
• On many vehicles, the size tells: AdBlue gets the smaller filler neck.
• The flap. Look inside your fuel flap for a label. Many vehicles say there which fuel goes where.
• The handbook says where it is when your filler isn't next to the diesel cap: the boot, or under the bonnet.
• Check with the person who drove it last — before you leave, not when the light comes on — when you pick up a hire or company car from somewhere like the car park outside Widnes.

Moss Bank: what occurs when we turn up

We come to the vehicle wherever it has stopped, whether that is outside St John Fisher Catholic Primary School, close to Future Flower or on your own driveway. The replies decide this work and the quote, so our technicians ask what went in, about how much, and whether it's run. You get that quote on the phone, before anybody sets off.

After that: a drain, then a thorough flush of the entire system. AdBlue crystallises and is corrosive to some of the metals in a fuel system, so it does not wash out on its own — which is why the flush matters more with AdBlue than with petrol. Testing comes last: before that, clean diesel goes in, and the fuel filter is cleaned or changed if necessary. We don't go until it has been started and is running correctly.

With pumps fine on a working forecourt and quiet enough to use outside a house at night, most jobs where your motor has not run take roughly half an hour once our engineers arrive. The insurer will ask for the engineer's report and the VAT invoice, and you get both once this job is done. Payment is on the day, with no money upfront. While we travel, have a look at your insurance documents; plenty carry cover for misfuelling.