--- title: AdBlue in a Diesel Tank Harefield? Read This canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/harefield-hampshire-so51-7/ location: Harefield county: Hampshire latitude: 50.995810 longitude: -1.472700 service: AdBlue in a Diesel Tank updated: 2026-10-11 --- # Preventing AdBlue in a Diesel Tank in Harefield: Why It Happens AdBlue already in the diesel tank? In that case put this page aside for now, keep your ignition and motor off, and phone 0333 366 0103. In Harefield, catching it before your engine turns normally leaves draining and a thorough flush on the spot. If you're reading before it has happened, the remainder of this page is about why it takes place and how to make sure it doesn't. ## AdBlue in a diesel car, and its separate tank Plenty of current diesels on the roads around Harefield and Cupernham carry two liquids, not one. Diesel goes to your engine. Its own tank holds it, and from there it goes to your exhaust, where a spray treats the fumes. There is a filler on every tank. Other vehicles keep the AdBlue filler in your boot or under the bonnet; a lot of others have the two together behind one flap. At the petrol pump, the diesel side gets filled all the time. Far less often, the AdBlue side is topped up — normally from a bottle, by someone working out where it goes. Mistakes happen in that gap between them. ## AdBlue in your diesel tank around Harefield: how it happens Carelessness seldom causes it. What does is three things lining up at once. The warning comes first. As AdBlue runs low the vehicle tells you, and if it runs out completely, your vehicle goes into limp mode. So the top-up is done in a hurry: on a driveway off St. Blaize Road before work, or in the car park at The Hunters Inn on the way home. Then, the hand reaches for the cap it knew on the old car — because a hire car, a new motor or a company car puts the fillers where your last one didn't. Third, the spout goes in: a diesel filler or AdBlue filler, it goes in as easily, and once the tip begins, nothing stops it. Crampmoor or the middle of Harefield: it is the same few seconds in both. ## Which filler is for AdBlue, and which for diesel? Look at these before pouring, on a forecourt in Harefield or a drive out in Whitenap. Seconds, that's all. - Where it sits misleads; the cap does not. AdBlue ones tend to be blue or bear the word "AdBlue" — diesel ones normally don't. - The size. On many vehicles the AdBlue filler neck is the smaller of the two. - Look inside the fuel flap: plenty of vehicles have a label there showing which fuel goes where. - In the boot or under the bonnet: that's where your filler is if it is not by your diesel cap, and the handbook tells you which. - Whoever had it before will know. Ask when you pick up a hire car or fleet car — at Romsey's car park, perhaps — rather than when the light appears. ## How to top up without AdBlue in your diesel tank When the light goes on, wherever across Hampshire, follow this routine. - Turn off after you park — level ground, engine off, and not rushed beside Primrose Way on the verge. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds silly and it does the trick. - The diesel cap stays on. When the two sit under a flap, make sure it is closed before lifting the bottle. - Stop when the tank is topped up or the bottle runs dry; until then, pour slowly using the built-in spout. - Only after that, start your car: close the cap, check once more, and make sure your diesel cap was never opened. If at step two or three you find you have already poured into your diesel side, stop there. Don't carry on to stage five. ## Already put AdBlue in the diesel tank around Harefield? The short order of things, beginning with not starting the motor. The fuel pump starts on plenty of diesels as soon as your ignition is switched on — so keep it off. AdBlue does not mix with diesel — it sinks to the bottom of the tank, where your fuel is drawn from — so do not top up with diesel to dilute it. The staff at Murco, BP or any forecourt will normally lend a hand pushing the car away if asked. At home in Harefield? Then your car stays where it is. When the motor has run by now, pull over somewhere safe and turn it off. Come off the Nursling Spur Motorway — under 3 miles out of Harefield — at the first exit. Tell us about how far it went: a run towards Southampton, under 10 miles away, is a bigger job than a short hop across Harefield. ## Harefield: what happens when our technicians arrive Outside Cupernham Junior School, near Woodley Village Hall or on your own drive: wherever your car has stopped, our engineers come to it. Both the work and our price rest on three replies — what liquid, what quantity, and if it's run — so our engineers ask. No one heads out before you have heard our price by phone. Then that tank is drained and your system flushed thoroughly. AdBlue crystallises and is corrosive to some of the metals in a fuel system, so it doesn't wash out on its own — which is why that matters more here than with petrol. The filter flushed or, if it must be, swapped; fresh diesel in; then a check of the vehicle. Then our engineers fire it up and confirm it runs correctly before we go. Most jobs are done in roughly half an hour once we get there, as long as your motor has not run — and the pumps we use are safe on a live forecourt yet quiet at night beside a house. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. Many insurance policies include misfuelling cover, so it's worth checking yours whilst we are on the way. ## About Harefield itself Harefield is a suburban area in Hampshire, situated on the riverside at an elevation of around 30 metres. Harefield lies near the city of Southampton, approximately 7 miles away, and is surrounded by nearby places such as Crampmoor, Woodley, and Halterworth. Harefield has a population of around 5453 people and is characterised by predominantly terraced housing. Harefield is also located within commuting distance of London, being around 68 miles away. ## AdBlue drains across Hampshire, Harefield included Woodley and Halterworth are among the towns around Harefield, a residential suburb, that the same vans cover, throughout SO postcodes. Quickest of all: give a SO51 7 postcode for the van. The vehicle does not need to move. A drive, a lay-by on the way to The Copse, a side street near St Swithun's Church: our engineers drain the car where it sits. Awkward to explain, like the back of Pond Cottage? Close to a county line? Asking is better than guessing, and so phone. ## The short version for Harefield people Before you tip, read the cap. If AdBlue has gone in the diesel tank regardless, leave the car off then ring 0333 366 0103. Petrol in Diesel drains it where it waits, anywhere across Hampshire.