How It Happens and How to Avoid It: AdBlue in a Diesel Tank in Haigh Moor

Two fillers, two tanks: AdBlue in a diesel car

Diesel feeds your engine — but many newer diesels seen round Haigh Moor and Beggarington Hill hold another fluid too. Its own tank holds it, and from there it is sent to your exhaust, and there a spray treats the fumes.

Every tank comes with one filler of its own. Under one flap, next to each other: that is the arrangement on many vehicles. On others, AdBlue's filler is beneath the bonnet or in the boot instead. The diesel side is topped up at the petrol pump all the time. Rarely filled, AdBlue normally goes in from a bottle, poured by someone who must stop and think what cap to use. That gap is where the error lives.

How to tell the AdBlue filler from the diesel one

A couple of seconds is all these take — so run through them before you pour anything, on a drive in Upper Green or a forecourt around Haigh Moor.

• Blue and marking: an AdBlue cap is often blue, or says "AdBlue", where a diesel cap normally does not. Go by the cap, not where it sits.
• The size. On plenty of vehicles the AdBlue filler neck is the smaller of the two.
• A label inside the fuel flap often says which fuel goes where, on many cars. Look for it.
• The handbook. If the filler is not by the diesel cap, it's in your boot or under the bonnet, and the handbook says which.
• Picking up a hire or company car, say at the car park outside Batley? Check with whoever drove the car last before you set off, rather than when the light comes on.

Haigh Moor: what happens when we arrive

Wherever the car came to rest, whether by Hill Top Primary Academy, near West Ardsley Methodist Church or at home, the van travels to it. Both the work and the quote rest on three replies — which fluid, what amount, and if it has run — so we ask. During the call itself, you hear our price — ahead of dispatch.

Draining the tank comes next, then a thorough flush of your system. More than with petrol, it matters here: crystals form, certain metals are attacked, and nothing washes away on its own, no matter how long it sits. Your filter is cleaned, or replaced where it needs to be; clean diesel goes in; and the car is tested. We do not go until it has been started and is running smoothly.

If your engine hasn't run, most jobs take about half an hour once we're there, using pumps that are fine on a working forecourt and quiet enough to use outside a house at night. Payment happens on the day, not upfront, and you receive the paperwork an insurer wants: an engineer's report and a VAT invoice. Plenty of insurance policies include misfuelling cover, and so it is worth checking yours whilst we're on the way.