--- title: Explained: AdBlue in a Diesel Tank Long Crendon canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/long-crendon-buckinghamshire/ location: Long Crendon county: Buckinghamshire latitude: 51.773370 longitude: -0.992170 service: AdBlue in a Diesel Tank updated: 2026-10-16 --- # Why It Occurs and How to Prevent It: AdBlue in a Diesel Tank in Long Crendon If AdBlue is already in your diesel tank, stop reading for a moment: leave the engine and the ignition off then phone 0333 366 0103. Around Long Crendon, catching it before your motor turns normally leaves a drain and a full flush where it stands. Not happened yet? Below, the page covers the reasons it takes place and the how to prevent it altogether. ## AdBlue in a diesel car: two tanks, two fillers Plenty of newer diesels in Thame, like those in Long Crendon, carry on two liquids; the engine gets just the diesel. Your exhaust, not your motor, is where AdBlue ends up: dosed into the gas to fresh them, from a separate tank. Separate tanks, different fillers. On a lot of vehicles the two sit side by side under the same flap; on others the AdBlue filler is in the boot or under the bonnet. The diesel side is topped up at the pump all the time. Much less frequently, the AdBlue side gets filled — mostly from a bottle, by a person thinking about where it goes. It's in that gap that the slip lives. ## How does AdBlue in the diesel tank take place around Long Crendon? Three things tend to come together, and carelessness is seldom one of them. The warning comes first. As AdBlue runs low the vehicle tells you, and if it runs out completely, the car goes into limp mode. So the top-up is done in a hurry: on a driveway off Fells Close before work, or in the car park at Eight Bells on the way home. Next, the hand reaches for the cap it knew on the old car — since a hire car, a new car or a company car places the fillers where your last one didn't. A spouted bottle meets no resistance at a diesel filler any more than at an AdBlue one. So the tip, once started, carries on. It's a few seconds, whether out in Easington or right in the heart of Long Crendon. ## Telling the AdBlue filler from your diesel filler Look at these before pouring, on a forecourt around Long Crendon or a drive over in Shabbington. A few seconds, that's all. - 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. - The size. On many vehicles the AdBlue filler neck is the smaller of the two. - The flap. Look inside your fuel flap for a label. Many motors say there which fuel goes where. - In your boot or under the bonnet: that's where your filler sits if it's not by the diesel cap, and the handbook tells you which. - Ask the person who drove it last — before you leave, not when the light comes on — if you collect a hire or company car from somewhere like the car park at Haddenham & Thame Parkway. ## AdBlue top-ups that never reach your diesel tank Anywhere across Buckinghamshire the light comes on, here is a routine for that day. - Park and switch off. Not on a slope, not with your engine running, and not in a rush on the side of Burt's Lane. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds daft and it does the trick. - Both under a single flap? Then confirm the lid on your diesel filler stays closed ahead of raising the bottle. - Pour slowly, using the bottle's own spout. Stop when it's full or when the bottle is empty. - Before starting the vehicle, close the cap and check again that your diesel cap never opened off. Stop there if you find, at step two or three, that you've already poured into the diesel side. Never go on to stage five. ## AdBlue in your diesel tank already, around Long Crendon? The short order of things, beginning with not starting your motor. On plenty of diesels the ignition alone runs the fuel pump, so don't switch the car on. Thinning it with more diesel fails, because AdBlue settles to the base instead of blending — and that's where your fuel is sucked from. The staff at Esso, BP or another forecourt will normally lend a hand to push the vehicle clear when asked. Your own drive around Long Crendon is where it should stay. Where your motor has run already, pull over safely and turn it off. On the M40, under 5 miles from Long Crendon, that means the next exit. A short hop across Long Crendon is a smaller job than a run towards Oxford, under 15 miles away, and so tell us about how far it went. ## Our arrival around Long Crendon, and what happens next By Long Crendon School, near The Church House or on your own driveway: wherever your car has stopped, our engineers come to it. Our engineers ask what went in, roughly how much, and whether it's run, since those replies settle this work and the price. Nobody sets off until you have had our price over the phone. Next: a drain, then a full flush of the whole system. Much more than with petrol, it counts with AdBlue: the crystals build up, some metals corrode, and nothing clears out unaided, no matter how long it sits. Once the fuel filter has been flushed — or renewed, where required — clean diesel is added, and then the vehicle is tested. We don't leave until it has been started and is running properly. Most jobs are done in about half an hour after our technicians arrive, provided your motor hasn't run — and the pumps we use are fine on a live forecourt yet quiet at night outside a house. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. Misfuelling cover is included in many insurance policies — and so make use of the wait to check yours. ## About Long Crendon and where it is Long Crendon is a village in Buckinghamshire, situated in the inland countryside of the South East region, with an elevation of around 104 metres. Long Crendon lies near the cities of Oxford and Aylesbury, and is close to the villages of Easington, Chilton, and Chearsley. Long Crendon has a population of approximately 2004 people, and its housing stock is predominantly made up of detached homes. Long Crendon is located about 41 miles from London, making it a commuter village with good transport links. ## Long Crendon and Buckinghamshire: AdBlue drains across the area Throughout HP postcodes, our vans covering Long Crendon — a rural village — work the surrounding spots too, Chearsley and Chilton included. The van reaches you fastest with a postcode starting HP18 9. There's no need to move the car. Our technicians drain it where it is — a side street near Long Crendon Library, a lay-by on the way to Long Crendon Recreational Ground, a driveway. If you're near a boundary, or somewhere hard to explain like the back of Long Crendon Village Centre, ring and ask instead of assuming. ## In short, for Long Crendon motorists Read the cap before you tip. AdBlue in your diesel tank regardless? Keep it switched off and call 0333 366 0103; Petrol in Diesel empties it where it stands, throughout Buckinghamshire.