--- title: AdBlue in a Diesel Tank Cwmtillery: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/cwmtillery-blaenau-gwent/ location: Cwmtillery county: Blaenau Gwent latitude: 51.743870 longitude: -3.136470 service: AdBlue in a Diesel Tank updated: 2026-10-16 --- # Cwmtillery: How Does AdBlue End Up in a Diesel Tank, and How Do You Avoid It? Leave your motor and ignition off and ring 0333 366 0103 now — reading can wait when AdBlue is already in your diesel tank. In Cwmtillery, catching it before your motor runs normally leaves a drain and a thorough flush on the spot. Nothing happened yet? Further down, the page covers the why it happens and the how to avoid it for good. ## AdBlue in a diesel motor: two tanks, two fillers Not one fluid but two: that's what plenty of newer diesels around Cwmtillery and Abertillery carry, with diesel feeding 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. There's a filler on every tank. Many of cars share a single flap for the two, while some put the AdBlue filler to the boot or under the bonnet. Diesel gets filled on every filling station call-out, again and again. The AdBlue side is topped up far less regularly, normally from a bottle, and usually by someone who has to stop and think where it goes. The error lives in that gap. ## How does AdBlue in the diesel tank happen around Cwmtillery? It's rarely carelessness. Three things tend to line up. On a driveway off Gwern Berthi Road before work, or in the car park at New Bridgend Inn heading home: that's where the hurried top-up takes place. Why the rush? As AdBlue runs low the car warns you, and if it is empty, limp mode follows. Next, the hand reaches for the cap it would have used on the old motor — because a hire car, a new car or a company car places the fillers somewhere your last one didn't. No part stops the tip once it has started, since a bottle with a spout goes into a diesel filler as easily as an AdBlue one. The bottle fits. It takes a few seconds, be it in Pen-y-Bont or right in the centre of Cwmtillery. ## Telling the AdBlue filler from your diesel filler Before you pour anything, whether on a drive in Pant y Pwdyn or a forecourt in Cwmtillery, check these. They take a few seconds. - Check the cap rather than going by position: AdBlue ones are frequently blue or marked "AdBlue", and diesel caps usually are not. - On many cars, the size tells: AdBlue has the smaller filler neck. - Look inside the fuel flap: many cars carry a label there showing which fuel goes where. - The handbook shows which it lives when the filler isn't next to the diesel cap: the boot, or under the bonnet. - Check with the person who drove it last — before you leave, not when the light comes on — if you pick up a hire or company car from somewhere like the car park at Ebbw Vale Parkway. ## AdBlue top-ups that never reach the diesel tank Wherever around Blaenau Gwent the light comes on, this is a routine for the day. - Pull in somewhere level, engine off, with time in hand — never rushing on the side of Tŷ Dan y Wal. - Locate the AdBlue filler, check the cap, and speak the name "AdBlue" out loud as you unscrew it. It sounds daft. It does the trick. - The diesel cap stays on. Where the two share a flap, make sure it is shut before lifting the bottle. - Tip slowly, using the bottle's own spout. Stop when it is full or when the bottle is empty. - Before starting the car, close the cap and look again that your diesel cap never opened off. Find at step two or three that it's already gone into the diesel side? Then stop just there. Step five stays off limits. ## Already put AdBlue in the diesel tank in Cwmtillery? Then the order of things is short. Do not start the engine. The fuel pump runs on many diesels the moment your ignition is switched on — so keep it off. Filling up with diesel will not weaken it: rather than mixing, AdBlue drops to the bottom of that tank, right where the fuel is taken from. Ask the attendants to help push the vehicle clear of the petrol pump if you are on a forecourt — the Tesco, the Gulf or somewhere else. Leave it where it is if you are on your own driveway in Cwmtillery. When your engine has run already, pull over somewhere safe and switch it off. Leave the M4 — under 15 miles out of Cwmtillery — at the first exit. About how far did it go? Crossing Cwmtillery is smaller work than a trip of under 15 miles towards Newport, and so say. ## When our technicians arrive in Cwmtillery, what takes place? Outside the local primary school, close to Blaenau Gwent Methodist Church or on your own drive: wherever your car has stopped, we come to it. Our engineers ask what went in, roughly how much, and if it's run, because those answers determine this work and our price. You get that price on the phone, before anybody heads out. Emptying the tank comes next, followed by a thorough flush of the fuel 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. Filter cleaned or, if it must be, replaced; fresh diesel in; and then a check of the vehicle. Next our technicians start the engine and confirm it runs properly before we go. Using pumps safe on a working forecourt and quiet enough to use outside a house at night, most jobs in which your motor hasn't run need roughly half an hour after our technicians arrive. No money in advance; you settle up that day. Afterwards, a VAT invoice and a report from the engineer go to you for the insurer. It's worth checking your policy as the van travels to you: misfuelling cover is included with plenty of policies. ## About Cwmtillery, briefly Cwmtillery is a suburban area situated in the valley of the Ebbw River in south Wales, with a mix of terraced housing and local amenities. Cwmtillery sits at an elevation of around 290 metres, overlooking the surrounding countryside and the nearby communities of Pen-y-Bont and East Bank. Cwmtillery is located near the city of Newport, which is approximately 12 miles away, and is part of the Blaenau Gwent county borough. Cwmtillery has a population of around 1277 people, according to recent estimates. ## AdBlue drains around Cwmtillery and across Blaenau Gwent Cwmtillery is a residential suburb, and our teams that cover it also work the places near it, Blaenau Gwent and East Bank among them, across the NP postcode area. A postcode starting NP13 1 gets the van to you fastest. The car does not need to shift. Wherever it sits — beside Wyndham Vowles Community Center, in a layby en route to Coed Castellau, at home — that's where it gets emptied. Ring and ask instead of assuming if you are near a boundary, or somewhere hard to describe, like the back of Blaenau Gwent Baptist Church. ## For Cwmtillery people, the short version Before you pour, read the cap. AdBlue in your diesel tank after all? Leave the vehicle off then call 0333 366 0103; Petrol in Diesel empties it on the spot, throughout Blaenau Gwent.