--- title: Frogmore: AdBlue in a Diesel Tank, Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/frogmore-hertfordshire/ location: Frogmore county: Hertfordshire latitude: 51.718020 longitude: -0.334850 service: AdBlue in a Diesel Tank updated: 2026-10-06 --- # How It Happens and How to Avoid It: AdBlue in a Diesel Tank in Frogmore 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. A drain plus a full flush, carried out just where your vehicle stands in Frogmore, is normally all it needs if found before your engine runs. Not happened yet? Below, the page covers the why it takes place and the how to prevent it altogether. ## AdBlue in a diesel motor: two tanks, two fillers Diesel goes to the engine — but plenty of modern diesels driven round Frogmore and Napsbury carry a second fluid as well. Your exhaust, not the motor, is where AdBlue ends up: sprayed into the gas to clean them, from a separate tank. Each tank has its own filler. Under one flap, next to each other: that is the layout on a lot of vehicles. On others, AdBlue's filler sits beneath the bonnet or in the boot instead. At the petrol pump, your diesel side gets filled constantly. The AdBlue side is filled far less commonly, usually from a bottle, and usually by somebody who has to stop and think where it goes. That gap is where the mistake lives. ## Frogmore: how AdBlue in your diesel tank occurs Seldom is it carelessness: normally three things coincide. Haste comes from the warning. The vehicle warns you as AdBlue runs low, and a dry tank sends the vehicle into limp mode — so the top-up gets done in a rush, before work on a drive off Moorlands, or on the way home in the car park at The Overdraught. The old car's cap is where the hand reaches — but a hire car, a new car or a company car puts the fillers elsewhere. That's the second factor: an unfamiliar vehicle. A spout-topped bottle meets no obstacle at a diesel filler no more than at an AdBlue one. So the tip, after begun, keeps on. Whether it happens in Park Street or the middle of Frogmore, it's the same few seconds. ## Telling the AdBlue filler from your diesel filler Whether a Frogmore forecourt or a driveway out in Napsbury Park, spend a few seconds over these before anything is poured in. - The cap. The AdBlue cap is frequently blue, or marked "AdBlue". Your diesel cap usually isn't. Read it rather than going by where it sits. - Plenty of motors give AdBlue the smaller neck of the two. - Lift the flap and look for a label — plenty of motors mark which goes in each filler just there. - Can't see it next to your diesel inlet? Then check below the bonnet or in your boot — the owner's manual says which. - The person who drove the vehicle last. On a hire or company car collected from somewhere like the car park at How Wood, ask before you leave, not when the light comes on. ## AdBlue top-ups that never reach the diesel tank When the light comes on, anywhere across Hertfordshire, use this routine. - Turn off after you park — level ground, motor stopped, and never in a rush beside Frederick Place 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. - If both sit under one flap, check your diesel cap is still closed before you lift the bottle — then leave it on. - Using the bottle's own spout, tip slowly — and stop when it is full or the bottle is empty. - Close the cap, then look once more — making sure the diesel cap remained shut the whole time. After that, start the vehicle. Find during the second or third stage that AdBlue went in the wrong tank? That's where you stop. Step five is out. ## Frogmore: already put AdBlue in your diesel tank? The short order of things, starting with not starting your engine. The fuel pump starts on many diesels the moment your ignition is switched on — and so leave it off. Do not top up with diesel to thin it: AdBlue doesn't mix with diesel, it sinks to the bottom of your tank, where the fuel is sucked from. If you are on a forecourt, whether it's the BP or the Shell, ask the staff to help push your car clear of the pump. If you're on your own driveway around Frogmore, leave the car where it sits. When the engine has run already, pull over somewhere safe then turn the car off. On the M25, under a mile from Frogmore, that means the next junction. About how far did it go? Crossing Frogmore is less work than a trip of under 3 miles to St Albans, so tell us. ## Frogmore: what takes place when our engineers turn up Anywhere the vehicle has stopped, whether by Park Street Church of England Voluntary Aided Primary School, beside Holy Trinity or at home, our van comes to it. What liquid got in, the quantity, and whether it ran: our technicians ask because those replies decide both work and quote. No one sets off until you've had our price over the phone. Draining your tank comes next, then a thorough flush of the fuel system. Much more than with petrol, it matters here: crystals form, certain metals are attacked, and nothing clears out on its own, however long it is left. The fuel filter is flushed, or replaced where it needs to be; clean diesel goes in; and your car is tested. Before we go, our technicians start the car and check that it's running properly. Most jobs are finished in about half an hour once we arrive, provided the motor hasn't run — and the pumps our engineers use are safe on a busy forecourt yet quiet after dark outside a house. Your insurer will ask for the engineer's report and the VAT invoice, and you get both once the job is done. Payment comes on the day, with no deposit. Many insurance policies include misfuelling cover, and so it is worth checking yours whilst we're on the way. ## About Frogmore, for a moment Frogmore is a village in Hertfordshire, situated on the riverside at an elevation of around 70 metres, with St Albans just 2.4 miles away. Frogmore has a mix of housing types, but is predominantly composed of flats, and is close to nearby places such as Park Street, How Wood, and Colney Street. Frogmore is located within commuting distance of London, approximately 17 miles away, making it a popular choice for those working in the capital. Frogmore remains a relatively small community, with a population of around 1169 residents. ## AdBlue drains around Frogmore, and Hertfordshire beyond Frogmore is a village, and the teams that cover it also work the towns near it, How Wood and Colney Street among them, across the AL postcode area. The van reaches you fastest with a postcode starting AL2 2. Moving the vehicle isn't needed. A driveway, a lay-by on the way to Stroud Wood, a side street close to Roman Villa: our engineers drain the vehicle where it sits. Ring and ask rather than guessing if you're near a border, or somewhere hard to explain, like the back of Park Street Baptist Church. ## Frogmore drivers: the short version First, the cap; after that, the tip. If AdBlue has gone in your diesel tank all the same, leave the car off and ring 0333 366 0103. Petrol in Diesel clears it where it sits, anywhere across Hertfordshire.