--- title: Headley Down: AdBlue in a Diesel Tank, Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/headley-down-hampshire/ location: Headley Down county: Hampshire latitude: 51.121630 longitude: -0.804860 service: AdBlue in a Diesel Tank updated: 2026-10-19 --- # AdBlue in a Diesel Tank in Headley Down: How It Happens and How to Prevent It If AdBlue is already in your diesel tank, stop reading for a moment: leave your engine and the ignition off and ring 0333 366 0103. Usually, when the engine hasn't turned, it is emptied and thoroughly flushed where the car is in Headley Down. The rest of this page explains why it takes place and how to ensure it does not — useful if you are reading ahead of time. ## AdBlue in a diesel motor: two tanks, two fillers Diesel feeds your motor — yet many modern diesels seen around Headley Down and Headley carry another liquid as well. AdBlue goes to your exhaust, where it is sprayed into the gas to fresh it, and it lives in a tank of its own. There is a filler for each tank. Under one flap, side by side: that's the layout on many cars. Elsewhere, AdBlue's filler sits under the bonnet or in the boot instead. Filling your diesel side at the pump happens constantly. Rarely topped up, AdBlue usually comes from a bottle, poured by someone who has to stop and think what filler it needs. That gap is where the mistake lives. ## How does AdBlue in your diesel tank happen around Headley Down? Three things tend to come together, and carelessness is rarely one of them. On a drive off Eddeys Lane before work, or in the car park outside The Crown heading home: that is where the rushed top-up happens. Why the rush? As AdBlue runs low your car warns you, and if it's gone, limp mode kicks in. Then the car is unfamiliar. A hire car, a new motor or a company car puts the fillers where your last one didn't, and your hand hits for the cap it would have used on the old one. Third, the bottle fits: a diesel filler or AdBlue one, it slides in just as readily, and once the tip starts, no part halts it. The same few seconds settle it, in the middle of Headley Down or out in Beech Hill. ## Which filler is for AdBlue, and which for diesel? A few seconds is all the checks take — so run through them before you tip anything, on a drive in Barford or a forecourt around Headley Down. - Check the cap rather than going by position: AdBlue caps are commonly blue or marked "AdBlue", and diesel ones normally aren't. - Look at the size: the smaller filler neck is, on plenty of cars, the AdBlue one. - A label inside your fuel flap often says which fuel goes where, on many motors. Check for it. - Can't find it next to the diesel filler? In that case look below the bonnet or in the boot — the owner's manual says where. - Ask the person who drove it last — before you leave, not when the light comes on — if you pick up a hire or company car from somewhere like the car park outside Liphook. ## Topping up AdBlue without it reaching the diesel tank For the day the warning appears — anywhere you are around Hampshire — a routine to follow. - Not in a rush on the side of Eddeys Close, not on a slope, not with your motor running: park then switch off first. - Silly as it sounds, saying "AdBlue" aloud while you unscrew the cap works — once you have found your filler and read it. - The two under one flap? Then confirm the cap on your diesel filler stays shut ahead of raising the bottle. - Finish once your tank is topped up or the bottle is empty; until then, pour gently using the own spout. - Close the cap and check again. Make sure your diesel cap was never opened. Only then start your car. Stop there if you find, at stage two or three, that you have already poured into your diesel side. Stage five is off limits. ## AdBlue in your diesel tank already, in Headley Down? Do not start the engine: that is where the short order of things starts. Keep your ignition off as well, because on plenty of diesels it by itself runs your pump. Filling up with diesel won't weaken it: rather than mixing, AdBlue sinks to the bottom of the tank, right where the fuel is taken from. The attendants at JET, BP or another forecourt will usually help pushing your car away when you ask. If you are on your own drive around Headley Down, leave it where it is. Where the engine has run already, stop safely and switch the vehicle off. Headley Down sits under 15 miles from the M3; there, use the first junction. A short hop across Headley Down is a smaller job than a run towards Chichester, under 25 miles away, so tell us roughly how far it went. ## What occurs when our technicians arrive around Headley Down Our technicians come to the car wherever it has stopped, whether that is outside The Holme Church of England Primary School, near St. Francis Church or on your own driveway. The answers determine the work and our quote, so we ask what went in, about how much, and whether it's run. That price is given on the call, before any van leaves. Then that tank is drained and your system cleaned thoroughly. With AdBlue that counts more than with petrol: it crystallises and is corrosive to some of the metals in a fuel system, and so it doesn't wash out on its own. The filter cleaned or, where it must be, swapped; fresh diesel in; then a test of the vehicle. The engine is fired up next and tested to be sure it runs properly, all before our engineers head off. Unstarted vehicles mostly mean a half-hour job from the moment we arrive. The equipment is fine on a live filling station, and quiet enough for a residential street late at night. Paying is on the day, not upfront, and you are given the documents your insurer asks for: an engineer's report and a VAT invoice. It is worth looking at your policy while we travel to you: misfuelling cover comes with plenty of policies. ## About Headley Down, briefly Headley Down is a village in Hampshire, situated inland at an elevation of 136 metres, and is located near the villages of Beech Hill and Arford. Headley Down has a population of approximately 1584 residents and is characterized by predominantly detached housing. Headley Down is positioned near the South Downs National Park and is within commuting distance to London, being around 39.6 miles away. Headley Down is also close to the city of Chichester, which is 19.7 miles away. ## AdBlue drains in Headley Down and across Hampshire Throughout GU postcodes, our teams that cover Headley Down — a rural village — work the surrounding places too, Hearn and Arford among them. Give a postcode beginning GU35 8, and the van arrives fastest. The car stays where it is. A driveway, a lay-by on the way to Headley Down Nature Reserve, a side street near Woodlands Community Hall: our engineers drain the vehicle where it sits. If you're close to a boundary, or somewhere hard to explain like the back of IN MEMORY OF PAULA WADHAMS, ring and ask rather than guessing. ## In short, for Headley Down motorists Read the cap before you pour. If AdBlue has gone in your diesel tank regardless, leave the vehicle off then phone 0333 366 0103. Petrol in Diesel drains it where it waits, anywhere across Hampshire.