--- title: Explained: AdBlue in a Diesel Tank Presdales canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/presdales-hertfordshire/ location: Presdales county: Hertfordshire latitude: 51.803490 longitude: -0.021700 service: AdBlue in a Diesel Tank updated: 2026-10-12 --- # AdBlue in a Diesel Tank in Presdales: How It Happens and How to Prevent It Stop here a minute if the diesel tank already has AdBlue in it: ignition off, engine off, and ring 0333 366 0103. A drain plus a full flush, done just where the vehicle sits around Presdales, is normally all it needs when caught before your motor runs. The remainder of this page explains why it occurs and how to make sure it doesn't — handy if you're reading before it has happened. ## Why does AdBlue in a diesel motor need its own filler? Many modern diesels around Pine Hurst, as well as Presdales, run on two fluids; the motor takes only your diesel. Stored in a tank of its own, AdBlue is fed into your exhaust gas and cleans it. Separate tanks, different fillers. Under one flap, next to each other: that is the layout on many cars. On others, AdBlue's filler sits under the bonnet or in the boot instead. The diesel side is topped up at the pump all the time. The AdBlue side is fuelled far less commonly, usually from a bottle, and normally by a person who has to stop and think where it goes. That gap is where the mistake lives. ## How AdBlue in your diesel tank occurs in Presdales Carelessness rarely explains it. Instead is three things coming up together. On a drive off Marsh Lane before work, or in the car park outside The Royal Oak on the way home: that's where the rushed top-up takes place. Why the rush? As AdBlue gets low the car warns you, and once it is gone, limp mode kicks in. Then the vehicle is new. A hire car, a new car or a company car puts the fillers where your last one didn't, and the hand reaches 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 after the pour starts, nothing stops it. Great Amwell or the heart of Presdales: it takes the same few seconds either way. ## Telling the AdBlue filler from the diesel filler Before you tip anything, whether on a drive in St Margarets or a forecourt around Presdales, check these. They take a few seconds. - Where it sits misleads; the cap does not. AdBlue caps tend to be blue or carry the word "AdBlue" — diesel ones usually do not. - Plenty of vehicles give AdBlue the smaller neck of the two. - Open the flap and check for a label — many vehicles show which goes in each filler right there. - In your boot or under the bonnet: that's where the 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 — when you pick up a hire or company car from somewhere like the car park outside Ware. ## Keeping AdBlue out of the diesel tank when you top up A routine for the day the light comes on, wherever around Hertfordshire that is. - Park then switch off. Not on a slope, not with your engine running, and not in a rush on the side of Post Wood Road. - Say "AdBlue" out loud as you unscrew the cap, after you find the AdBlue filler and read it. Daft, yes, but it works. - Leave your diesel cap on. If both sit under one flap, check the diesel cap is still closed before you lift the bottle. - Using the bottle's own spout, tip slowly — and stop when it's full or the bottle is empty. - Close the cap and check a second time. Make sure your diesel cap was never opened. Only then start the vehicle. Find at stage two or three that it's already gone into your diesel side? Then stop just there. Don't carry on to step five. ## Presdales: already put AdBlue in your diesel tank? Do not start the engine: that is where the short order of things starts. The fuel pump starts on plenty of diesels the moment your ignition is switched on — so leave it off. Don't top up with diesel to thin it: AdBlue doesn't mix with diesel, it sinks to the bottom of your tank, where your fuel is sucked from. The staff at Esso, BP or another forecourt will normally lend a hand pushing your car clear if you ask. Your own driveway around Presdales is the place it stays. Stop as soon as it is safe then switch off, if the engine has already run. The next exit is the place to come off when you're on the M11, under 10 miles from Presdales. A short hop across Presdales is a smaller job than a run towards St Albans, under 15 miles away, so tell us roughly how far it went. ## Presdales: what takes place when our technicians get there Outside Christ Church CofE (VA) Primary School and Nursery, near Ware Drill Hall or on your own drive: wherever your car has stopped, we come to it. We ask what went in, about how much, and if it's run, since the answers settle the work and the price. You get that price on the phone, before anyone heads out. Draining the tank comes next, followed by a full flush of the system. With AdBlue that matters more than with petrol: it crystallises and is corrosive to some of the metals in a fuel system, so it doesn't wash out on its own. Testing is at the end: before that, clean diesel goes in, and the filter is cleaned or replaced as needed. We do not go until it has been started and is running correctly. Unstarted vehicles usually need a half-hour job after the moment we arrive. The kit is safe on a busy filling station, and quiet enough for a driveway after dark. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. It's worth looking at your insurance while we travel to you: misfuelling cover comes with many policies. ## About Presdales, for a moment Presdales is a locality situated on the lakeside in Hertfordshire, with an elevation of 33 metres. Presdales lies approximately 21 miles north of London and 14 miles southeast of St Albans, near the communities of Great Amwell, Ware, and Rush Green. Presdales is characterized by its predominant flat housing and a population of around 550 residents. ## Presdales and Hertfordshire: AdBlue drains across the area Presdales is a small village, and the teams that cover it also work the places near it, Ware and Rush Green among them, across the SG postcode area. A postcode starting SG12 9 gets the van to you fastest. Your car stays where it is. Wherever it stands — near Scott's Grotto, on a lay-by en route to Post Wood, on a drive — that's where it gets emptied. Awkward to pin down, like the back of 3rd Ware Scout HQ? Close to a border? Asking is better than assuming, and so phone. ## Presdales motorists: the short version Always, the cap; then, the tip. AdBlue in the diesel tank regardless? Keep it switched off and call 0333 366 0103; Petrol in Diesel drains it on the spot, across Hertfordshire.