--- title: AdBlue in a Diesel Tank Furnace: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/furnace-carmarthenshire-sa15-4/ location: Furnace county: Carmarthenshire latitude: 51.690870 longitude: -4.167930 service: AdBlue in a Diesel Tank updated: 2026-10-17 --- # Why It Happens and How to Avoid It: AdBlue in a Diesel Tank in Furnace Leave the engine and ignition off then ring 0333 366 0103 now — reading can wait when AdBlue is already in your diesel tank. A drain plus a thorough flush, carried out right where your vehicle sits around Furnace, is usually what it needs when found before the engine runs. The rest of this page covers why it occurs and how to ensure it doesn't — handy if you are reading before it has happened. ## Why does AdBlue in a diesel car need its own filler? Not one liquid but two: that's how plenty of modern diesels around Furnace and Sandy run, with diesel feeding the engine. The exhaust, not your engine, is where AdBlue goes: dosed into the gas to fresh them, from its own tank. Each tank has its own filler. Many of motors have a single flap for the two, while some put the AdBlue filler to your boot or under the bonnet. At the pump, the diesel side gets filled constantly. Someone who has to stop and think where it goes normally tops up the AdBlue side, from a bottle, and much less frequently. The mistake grows in that gap between the two. ## Furnace: how AdBlue in your diesel tank takes place It is rarely carelessness. Three things tend to line up. On a drive off Cwm Terrace before work, or in the car park outside Stradey Arms heading home: that is where the rushed top-up takes place. Why the rush? As AdBlue runs low the car warns you, and once it's empty, limp mode follows. Unfamiliar motors come second, as well. Rentals, new cars and company cars place their fillers in new places, and the hand reaches 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, so nothing stops the pour after it has started. Whether it takes place in Pentre-Poeth or the middle of Furnace, it's the same few seconds. ## How to tell the AdBlue filler from the diesel one Whether a Furnace forecourt or a drive over in Llanelli, take a couple of seconds on these before any goes in. - Position misleads; the cap does not. AdBlue ones tend to be blue or bear the name "AdBlue" — diesel caps normally don't. - Plenty of vehicles give AdBlue the smaller filler of the two. - A label inside the fuel flap often shows which fuel goes where, on plenty of cars. Check for it. - Cannot see it beside your diesel inlet? In that case look below the bonnet or in the boot — the owner's manual says where. - The previous driver will know. Check when you collect a hire car or fleet car — at Llanelli's car park, perhaps — not once the warning comes on. ## How to top up without AdBlue in the diesel tank The day the light comes on, wherever across Carmarthenshire, follow this routine. - Pull in on level, motor off, with time in hand — not rushing on the side of Ynys-y-Cwm Road. - Locate the AdBlue filler, read the cap, and speak the name "AdBlue" out loud while you unscrew it. It seems silly. It does the trick. - Leave your diesel cap on. If both sit under one flap, check your diesel cap is still closed before you lift 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 look again — making sure your diesel filler remained closed the whole time. After that, start the car. Discover at the second or third step that the bottle went in the wrong filler? That is where you stop. Do not go on to step five. ## Furnace: already put AdBlue in your diesel tank? Do not start your motor: that is how the short order of things starts. Don't switch your ignition on; on plenty of diesels that alone runs the fuel pump. Do not top up with diesel to dilute it: AdBlue does not mix with diesel, it sinks to the bottom of your tank, where the fuel is drawn from. Ask the staff to help roll your car away from the pump if you are on a forecourt — the Asda, the Texaco or anywhere else. If you are on your own drive in Furnace, leave it where it stands. If the motor has already run, stop as soon as it is safe and switch off. Furnace sits under 5 miles from the M4; on it, take the first junction. Distance counts — a quick hop across Furnace is a smaller job than heading under 15 miles towards Swansea — so tell us roughly how far it went. ## What occurs when our technicians arrive in Furnace Anywhere the car came to rest, be it by the local primary school, beside Gorsedd Stone Circle or on your own drive, our van comes to it. Both the work and the price rest on three answers — which fluid, which quantity, and whether it's run — so our engineers ask. You hear that price on the phone, before anybody heads out. Next: a drain, then a full flush of the whole system. Much more than with petrol, it counts with AdBlue: crystals form, some metals are attacked, and none of it clears away on its own, no matter how long it is left. Once the filter is cleaned — or renewed, where required — clean diesel is added, and finally your vehicle gets tested. After that our technicians start it and check it runs properly before leaving. With pumps fine on a working forecourt and quiet enough to use outside a house at night, most jobs in which your motor has not run need roughly half an hour once we are there. Payment happens on the day, not upfront, and you receive the documents your insurer asks for: an engineer's report and a VAT invoice. Before we get there, have a look at your policy; plenty include cover for misfuelling. ## About Furnace Furnace is a coastal suburban area in Carmarthenshire, situated near the city of Swansea and overlooking the Bristol Channel. Furnace has a relatively low elevation of 22 metres and is surrounded by nearby places such as Pentre-Poeth and Mount Pleasant. Furnace is characterised by its predominantly semi-detached housing stock, which reflects the area's residential nature. Furnace is located approximately 10.9 miles from Swansea, making it a commuter-friendly location. ## AdBlue drains around Furnace and across Carmarthenshire Over SA postcodes, the teams that cover Furnace — a residential suburb — work the surrounding places too, Tyrfran and Mount Pleasant among them. Give a postcode beginning SA15 4, and the van arrives fastest. The vehicle does not need to move. Wherever it sits — beside Parc Howard Museum, on a layby heading to Parc Howard, on a drive — that is where it gets cleared. Ring and ask instead of assuming if you're near a border, or somewhere hard to describe, like the back of Llanelli Bowling Club. ## For Furnace people, the short version Before you tip, read the cap. If AdBlue has gone in the diesel tank all the same, leave the car off then ring 0333 366 0103. Petrol in Diesel drains it where it sits, anywhere across Carmarthenshire.