--- title: Aldgate: AdBlue in a Diesel Tank, Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/aldgate-greater-london/ location: Aldgate county: Greater London latitude: 51.513200 longitude: -0.077700 service: AdBlue in a Diesel Tank updated: 2026-10-18 --- # Aldgate: How Does AdBlue End Up in a Diesel Tank, and How Do You Avoid It? If AdBlue is already in your diesel tank, stop reading for a moment: leave the engine and your ignition off then call 0333 366 0103. Usually, if the engine has not run, it's emptied and fully cleaned where your vehicle sits in Aldgate. If you're reading before it has happened, the rest of this page is about why it takes place and how to make sure it doesn't. ## Two fillers, two tanks: AdBlue in a diesel vehicle Not one liquid but two: that's what plenty of newer diesels near Aldgate and Wapping run, with diesel for your motor. AdBlue goes to the exhaust, where it is sprayed into the gas to clean it, and it lives in a tank of its own. Separate tanks, different fillers. Under one flap, next to each other: that's the arrangement on a lot of cars. Elsewhere, AdBlue's filler sits beneath the bonnet or in your boot instead. The diesel side is filled at the pump all the time. Much less regularly, the AdBlue side is topped up — normally from a bottle, by a person thinking about where it goes. The mistake grows in that gap between the two. ## How does AdBlue in the diesel tank happen around Aldgate? Carelessness seldom explains it. Instead is three things lining up at once. On a drive off Aldgate before work, or in the car park outside The Craft Beer Co heading home: that is where the rushed top-up takes place. Why the rush? As AdBlue gets low the vehicle tells you, and once it is gone, limp mode kicks in. New-to-you cars are next, too. Hire cars, new vehicles and company vehicles put their fillers differently, and the hand goes for the cap it used on the old one. And the bottle fits. A bottle with a spout goes into a diesel filler as easily as an AdBlue one, and so nothing stops the pour after it has started. Tower Hill or the middle of Aldgate: it takes the same few seconds either way. ## Which filler is for AdBlue, and which for diesel? A couple of seconds is all these take — so run through them before you tip anything, on a drive in London or a forecourt around Aldgate. - The cap. The AdBlue cap is often blue, or marked "AdBlue". Your diesel cap usually is not. Read it instead of going by where it sits. - Many motors fit AdBlue the smaller neck of the two. - A label inside the fuel flap frequently shows which fuel goes where, on plenty of motors. Check for it. - Cannot see it next to your diesel filler? In that case look below the bonnet or in your boot — the owner's manual says which. - The previous driver knows. Check as you collect a hire car or company car — from London Fenchurch Street's car park, say — rather than once the light appears. ## How to top up without AdBlue in the diesel tank When the light comes on, wherever around Greater London, follow this routine. - Pull in somewhere level, engine off, with time in hand — never hurried on the side of Leadenhall Street. - Locate the AdBlue filler, check the cap, and say the name "AdBlue" aloud as unscrewing it. It sounds silly. It does the trick. - Both under one flap? Then confirm the cap on your diesel side is still closed before lifting the bottle. - Tip slowly, using the bottle's own spout. Stop when it is full or when the bottle is empty. - Shut the cap, and check again — confirm the diesel filler remained shut the whole time. After that, start the vehicle. Spot at stage two or three that it has already gone into your diesel side? Then stop right there. Leave out step five entirely. ## Put AdBlue in your diesel tank in Aldgate already? Do not start your motor: that is where the short order of things begins. On many diesels your ignition alone runs the fuel pump, so do not switch the vehicle on. Filling up with diesel won't dilute it: rather than mixing, AdBlue sinks to the base of your tank, just where the fuel is drawn from. Ask the attendants to help push the car clear of the pump if you're at a forecourt — the Shell, the Texaco or anywhere else. On your own drive in Aldgate? So the vehicle stays put. If the engine has already run, stop as soon as it is safe then switch off. Aldgate lies under 10 miles from the M11; there, take the next exit. Roughly how far did it go? Hopping across Aldgate is less a job than a run of under a mile towards London, and so tell us. ## When we turn up around Aldgate, what happens? Wherever the vehicle came to rest, whether outside The Aldgate School, near Priory of the Holy Trinity or on your own drive, our van travels to it. The replies determine the work and our price, so our engineers ask what got in, roughly how much, and if it's run. You hear that price on the phone, before anyone heads out. Then the tank is emptied and the fuel system purged thoroughly. Unlike petrol, AdBlue leaves crystals and eats at certain fuel-system metals, and none of that clears out unaided. That is why it counts more. After your filter has been cleaned — or replaced, where required — clean diesel goes in, and finally the car is tested. Before we leave, we start the engine and check that it's running correctly. Most jobs are done in about half an hour once our technicians arrive, as long as the motor has not run — and the pumps our technicians use are fine on a busy forecourt and 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. Wrong-fuel cover is included in plenty of insurance policies — and so make use of the wait to check yours. ## About Aldgate, for a moment Aldgate is a suburban area in East London, situated near the River Thames and close to the city's financial district. Aldgate sits at a low elevation of around 10 metres, with many of its residents living in flats. Aldgate is surrounded by other notable areas, including Tower Hill, Whitechapel, and Spitalfields, and is home to a population of approximately 11,300 people. Aldgate is also very close to the centre of London, being only 0.6 miles away from the city. ## Aldgate and Greater London: AdBlue drains across the area Aldgate is a residential suburb, and our vans that cover it also work the places near it, Whitechapel and Spitalfields among them, across the EC3M postcode area. Fastest of all: quote a EC3M 4 postcode to our van. The vehicle stays put. Anywhere it stands — beside The Great Escape, on a lay-by heading to St Katharine Cree Churchyard, at home — that's where it is cleared. Ring and ask rather than assuming if you are near a border, or somewhere hard to describe, like the back of Climb. ## The short version for Aldgate motorists Before you pour, read the cap. Petrol in Diesel drains it where it stands, anywhere in Greater London, if AdBlue has gone in the diesel tank anyway — and so leave the car off and call 0333 366 0103.