--- title: AdBlue in a Diesel Tank Royston? Read This canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/royston-hertfordshire/ location: Royston county: Hertfordshire latitude: 52.048250 longitude: -0.019990 service: AdBlue in a Diesel Tank updated: 2026-10-14 --- # Royston: How Does AdBlue End Up in a Diesel Tank, and How Do You Prevent It? AdBlue already in your diesel tank? Then put this page down a moment, leave the ignition and engine off, then phone 0333 366 0103. Usually, if the motor has not turned, it's emptied and thoroughly flushed where the vehicle is around Royston. Here before the event? In that case what follows covers why it comes about and how to prevent it happening at all. ## Two fillers, two tanks: AdBlue in a diesel car Many newer diesels in Reed End, as well as Royston, run on two liquids; the motor takes only the diesel. 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 on every tank. Plenty of motors share a single flap for both, whereas others move the AdBlue filler to the boot or under the bonnet. Diesel goes in on every forecourt visit, week in, week out. The AdBlue side is filled far less frequently, normally from a bottle, and normally by someone who has to stop and think where it goes. The slip lives in that gap. ## How AdBlue in your diesel tank happens in Royston It is rarely carelessness. Three things tend to line up. On a drive off A10 before work, or in the car park outside The Banyers on the way home: that's where the hurried top-up takes place. What is the reason for the rush? As AdBlue runs low the car warns you, and if it is empty, limp mode follows. The old car's cap is where the hand goes — yet a rental car, a new car or a company car keeps the fillers elsewhere. That's a second factor: an unfamiliar motor. No part halts the pour once it has started, since a bottle with a spout goes into a diesel filler as easily as an AdBlue one. The bottle fits. The same few seconds settle it, in the middle of Royston or out in Kneesworth. ## Telling the AdBlue filler from your diesel filler Look at these first, on a forecourt around Royston or a drive out in Barley. A few seconds, no more. - Check the cap instead of going by where it sits: AdBlue ones are frequently blue or marked "AdBlue", and diesel ones usually aren't. - Check the size: the smaller neck is, on plenty of cars, the AdBlue one. - Look inside your fuel flap: plenty of motors have a label there saying which fuel goes where. - In the boot or under the bonnet: that is where your filler is 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 the nearest station. ## Topping up AdBlue without it reaching the diesel tank A routine for the day the light comes on, wherever across Hertfordshire that is. - Park then switch off. Not on a slope, not with the engine running, and not in a rush on the side of Melbourn Street. - Say "AdBlue" out loud as you unscrew the cap, once finding the AdBlue filler and reading it. Silly, perhaps, yet it works. - The diesel cap stays on. When both share a flap, make sure it's closed before the bottle comes up. - Tip slowly, using the bottle's own spout. Stop when it's full or when the bottle is empty. - Shut the cap, and look once more — confirm the diesel filler remained closed the whole time. After that, start the vehicle. Stop there if you find, at stage two or three, that you've already poured into your diesel side. Skip step five entirely. ## Already put AdBlue in the diesel tank in Royston? Then the order of things is short. Don't start your engine. The fuel pump runs on plenty of diesels as soon as your ignition goes on — so leave it off. Diluting it with more diesel won't work, since AdBlue settles to the base rather than mixing — and that's where your fuel is sucked from. At a forecourt — Esso, Tesco or any other — the attendants will normally help push your car clear, when you ask. If you're on your own driveway around Royston, leave it where it stands. If the motor has already run, stop as soon as it is safe and switch off. The next junction is the place to come off when you are on the M11, under 10 miles from Royston. Distance counts — a quick hop across Royston makes a smaller job than heading under 15 miles towards Cambridge — so say about how far it went. ## What happens when we get there in Royston We come to the car wherever it has stopped, whether that's outside St Mary Roman Catholic Primary School, near Royston Town Hall or on your own drive. Those answers decide this work and the price, and so our technicians ask what was put in, about how much, and if it's run. On the phone call itself, you are told our price — ahead of anything else. Draining the tank comes next, followed by a full flush of the fuel system. 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. Once your filter is cleaned — or renewed, if needed — fresh diesel goes in, and then the vehicle gets tested. The motor is fired up next and tested to be sure it runs correctly, all before our engineers leave. If the engine hasn't run, most jobs take about half an hour once we're there, using pumps that are safe on a working forecourt and quiet enough to use outside a house after dark. Your insurer will ask for an engineer's report and the VAT invoice, and you get both once this job is done. Payment is on the day, with no deposit. Before we get there, have a look at your insurance documents; many include cover for misfuelling. ## About Royston, for a moment Royston is a town in Hertfordshire, situated approximately 37.7 miles north of London and 12.3 miles south of Cambridge. Royston lies in a relatively low-lying area, with an elevation of around 66 metres, and is surrounded by nearby places such as Kneesworth, Therfield, and Bassingbourn. Royston has a population of around 16729 people, with a predominance of semi-detached housing stock. Royston is a typical example of a commuter town, with many residents travelling to nearby cities for work. ## AdBlue drains about Royston, and Hertfordshire beyond Being a town, Royston has the same vans as nearby places — Therfield, Bassingbourn — all the way across SG postcodes and the surrounding area around them. Give a postcode that starts SG8 7, and the van gets there quickest. The car remains put. A driveway, a lay-by on the way to Priory Gardens, a side street close to Royston Picture Palace: we drain the vehicle where it is. Assuming doesn't help at the back of American 91st (H) Bomb Group memorial, on a boundary, or anywhere hard to pin down; phone and check. ## For Royston people, the short version Tip nothing till you've read the cap. Even so AdBlue in the diesel tank? Petrol in Diesel will drain it wherever it stands, anywhere across Hertfordshire: switch the car off and call 0333 366 0103.