--- title: Explained: AdBlue in a Diesel Tank Leatherhead canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/leatherhead-surrey/ location: Leatherhead county: Surrey latitude: 51.296160 longitude: -0.331120 service: AdBlue in a Diesel Tank updated: 2026-10-06 --- # AdBlue in a Diesel Tank in Leatherhead: How It Occurs and How to Avoid It AdBlue already in your diesel tank? Then put this page aside for now, keep the ignition and motor off, then ring 0333 366 0103. Normally, if your engine hasn't turned, it's drained and thoroughly rinsed where the car sits around Leatherhead. Not happened yet? Further down, the page explains the why it happens and the ways to avoid it for good. ## Two fillers, two tanks: AdBlue in a diesel motor Not one liquid but two: that's how plenty of newer diesels around Leatherhead and Givons Grove run, with diesel feeding your engine. AdBlue's own tank holds it, and from there it goes to the exhaust, where a spray treats the gas. There is a filler on each tank. Many of cars share a single flap for the two, whereas some move the AdBlue filler to the boot or under the bonnet. The diesel side is fuelled at the pump all the time. Much less regularly, the AdBlue side is filled — normally from a bottle, by a person thinking about where it goes. That gap is where the mistake lives. ## How AdBlue in the diesel tank happens around Leatherhead Carelessness seldom causes it. Instead is three things coming up at once. On a driveway off Bull Hill before work, or in the car park outside The Penny Black on the way home: that's where the hurried top-up happens. Why the rush? As AdBlue gets low the car tells you, and once it is empty, limp mode kicks in. Then the vehicle is new. A hire car, a new motor or a company car puts the fillers where your last one did not, and the hand hits for the cap it would have used on the old one. No part stops the pour after it has started, because a bottle with a spout goes into a diesel filler as readily as an AdBlue one. The bottle fits. Fetcham Grove or the middle of Leatherhead: it is the same few seconds either way. ## The AdBlue filler and your diesel filler: telling them apart Check these first, at a forecourt around Leatherhead or a driveway out in Tyrrells Wood. Seconds, that's all. - The cap. The AdBlue cap is frequently blue, or marked "AdBlue". Your diesel cap normally is not. Read it instead of going by position. - Look at the size: the smaller neck is, on plenty of vehicles, the AdBlue one. - Lift the flap and look for a label — many motors mark which belongs in which inlet right there. - Cannot find it beside your diesel inlet? Then check beneath the bonnet or inside the boot — the owner's manual says which. - Picking up a hire or company car, perhaps at the car park outside the nearest station? Ask the person who drove the car last before leaving, rather than when the light comes on. ## Topping up AdBlue without it reaching the diesel tank On the day the light comes on — anywhere you are around Surrey — a simple routine to use. - Switch off after you park — flat ground, motor off, and never rushed beside North Street at the roadside. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds silly and it works. - Leave your diesel cap on. If both sit under one flap, check your diesel cap is still closed before you lift the bottle. - Slowly does it, through the bottle's own spout, till it is full or the bottle runs out. - Only then, start your car: close the cap, check a second time, and make sure the diesel cap was never opened. Spot at step two or three that it's already gone into your diesel side? So stop right there. Stage five stays out. ## AdBlue in the diesel tank already, in Leatherhead? Do not start the engine: that is where the short order of things begins. On plenty of diesels the ignition alone runs the fuel pump, so don't switch it on. Thinning it with extra diesel won't work, because AdBlue sinks to the base rather than blending — and that is where the fuel is drawn from. The staff at BP, Esso or any forecourt will normally help pushing the vehicle away when asked. If you are on your own driveway in Leatherhead, leave it where it sits. If the engine has already run, stop as soon as it is safe then switch off. The next exit means where to come off when you're on the M25, under a mile from Leatherhead. A short hop across Leatherhead is a smaller job than a run towards Westminster, under 25 miles away, and so tell us roughly how far it went. ## When our engineers get there in Leatherhead, what occurs? Outside Leatherhead Trinity School and Nursery, close to Leatherhead War Memorial or on your own driveway: wherever your car has stopped, our technicians come to it. We ask what got in, about how much, and if it's run, because those answers decide the work and the quote. On the call itself, you are told our price — ahead of anything else. Next: draining, then a thorough flush of the entire system. More than with petrol, it counts with AdBlue: crystals form, certain metals corrode, and none of it washes out on its own, however long it is left. The filter cleaned or, where it must be, replaced; fresh diesel in; then a test of your car. Then we start it and check it runs correctly before we leave. Using pumps fine on a working forecourt and quiet enough to use outside a house at night, most jobs in which your engine hasn't run take about half an hour once our technicians arrive. No money in advance; you settle up on the day. Afterwards, the VAT invoice and the report from the engineer are handed to you for the insurer. While we travel, take a look at your insurance documents; many include cover for misfuelling. ## About Leatherhead itself Leatherhead is a town in Surrey, situated on the River Mole at an elevation of around 45 metres. Leatherhead lies approximately 17 miles south of central London, with good transport links to the city. Leatherhead has a mix of housing types, but is predominantly composed of flats, and is surrounded by areas such as Fetcham Grove and Leatherhead Common. Leatherhead is a significant settlement in the area, with a population of around 13,500 people. ## AdBlue drains about Leatherhead, and Surrey beyond Hawks Hill and Leatherhead Common are among the places near Leatherhead, a riverside town, that the same teams cover, over KT postcodes. A postcode starting KT22 7 gets our van to you fastest. Your car doesn't need to move. The drain happens on the spot, whether a driveway, a road by The Swan Centre, or a layby on the way to Mansion Gardens. If you are close to a border, or somewhere hard to describe like the back of The Leatherhead Theatre, ring and ask instead of assuming. ## The short version for Leatherhead people Read the cap before you tip. If AdBlue has gone in the diesel tank anyway, leave the car off and call 0333 366 0103. Petrol in Diesel empties it where it stands, anywhere around Surrey.