--- title: AdBlue in a Diesel Tank Ponthir: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/ponthir-torfaen/ location: Ponthir county: Torfaen latitude: 51.630570 longitude: -2.973970 service: AdBlue in a Diesel Tank updated: 2026-10-12 --- # Ponthir: How Does AdBlue End Up in a Diesel Tank, and How Do You Avoid It? Leave the engine and ignition off and ring 0333 366 0103 now — the rest can wait if AdBlue is already in the diesel tank. Caught before your engine runs, it is generally a drain and a thorough flush, done where the vehicle is in Ponthir. Nothing happened yet? Further down, the page covers the why it takes place and the ways to prevent it altogether. ## AdBlue in a diesel motor, and its separate tank Many modern diesels on the roads about Ponthir and Llantarnam carry two liquids, not one. Diesel goes to the engine. Kept in a tank of its own, AdBlue is fed into the exhaust stream and cleans it. Different tanks, separate fillers. On a lot of cars the two sit side by side under the same flap; on others the AdBlue filler is in your boot or under the bonnet. At the pump, your diesel side is topped up all the time. Much less commonly, the AdBlue side is topped up — mostly from a bottle, by someone thinking about where it goes. It's in the gap that the mistake happens. ## How does AdBlue in the diesel tank occur in Ponthir? Rarely is it carelessness: normally three things line up. On a drive off Station Road before work, or in the car park at The Star Inn heading home: that is where the hurried top-up happens. Why the rush? As AdBlue gets low the vehicle tells you, and if it is empty, limp mode follows. Then the car is strange. A hire car, a new motor or a company car puts the fillers where your last one did not, and your hand hits for the cap it would have used on the old one. Lastly, the spout goes in: diesel filler or AdBlue filler, it goes in as readily, and after the tip begins, nothing halts it. Llanfrechfa or the heart of Ponthir: it takes the same few seconds in both. ## Telling the AdBlue filler from your diesel filler Before you pour anything, whether on a driveway in Croes-y-mwyalch or a forecourt around Ponthir, check these. They take a couple of seconds. - Check the cap instead of going by where it sits: AdBlue ones are often blue or marked "AdBlue", and diesel ones normally aren't. - On plenty of motors, the size gives it away: AdBlue gets the smaller filler neck. - Open the filler flap and look for a label — many motors mark which belongs in which filler just there. - The handbook shows where it lives when your filler isn't next to the diesel cap: your boot, or under the bonnet. - Picking up a hire or company car, say at the car park outside Cwmbran? Ask whoever drove the car last before leaving, rather than once the light goes on. ## Topping up AdBlue without it reaching your diesel tank On the day the light comes on — wherever you are across Torfaen — a routine to follow. - Not in a rush on the side of Caerleon Road, not on a slope, not with the engine running: park then switch off properly. - Find the AdBlue filler, read the cap, and speak the word "AdBlue" out loud while unscrewing it. It sounds silly. It works. - If both sit under one flap, check your diesel cap is still closed before you lift the bottle — and leave the car on. - Stop when your tank fills or the bottle runs dry; before that, tip slowly through its own spout. - Close the cap and check again. Make sure your diesel cap was never opened. Only then start the vehicle. Discover at the second or third stage that the bottle went into the wrong filler? That is where you stop. Leave out stage five entirely. ## Put AdBlue in the diesel tank around Ponthir already? Do not start your motor: that is how the short order of things begins. Leave the ignition off too, since on plenty of diesels it by itself runs your pump. AdBlue does not mix with diesel — it sinks to the bottom of that tank, where the fuel is drawn from — so don't top up with diesel to thin it. At a forecourt — JET, BP or any other — the staff will normally help push the car clear, when you ask. If you are on your own drive in Ponthir, leave the vehicle where it is. Already run? Stop when it is sensible, then turn off. On the M4, under 3 miles from Ponthir, that means the next exit. Tell us about how far it went: a run towards Newport, under 5 miles away, is a bigger job than a short hop across Ponthir. ## What happens when we arrive in Ponthir Wherever your car came to rest, whether by the local primary school, beside Zion Baptist Church Ponthir or on your own drive, the van travels to it. Those replies determine the work and the price, and so our engineers ask what got in, about how much, and whether it's run. You hear that quote by phone, before anybody sets off. Draining your tank comes next, followed by a full flush of your system. Not like petrol, AdBlue forms crystals and eats at certain fuel-system metals, and none of it washes out unaided. Hence it counts more. A test is last: before that, clean diesel is added, and the fuel filter is cleaned or replaced if necessary. The engine is started next and tested to make sure it runs properly, all before our engineers go. Most jobs are finished in about half an hour once we arrive, as long as your motor has not run — and the pumps our technicians use are fine on a busy forecourt and quiet at night beside a house. Payment is on the day, not upfront, and you are given the paperwork your insurer wants: an engineer's report and a VAT invoice. It's worth looking at your policy while we travel to you: misfuelling cover is included with plenty of policies. ## About Ponthir and where it is Ponthir is a small village in Torfaen, situated on the banks of a river at a low elevation of around 20 metres. Ponthir lies close to the city of Newport, which is approximately 3 miles away, and is near other local places such as Llanfrechfa and Gatlas. Ponthir has a population of around 1260 people and predominantly consists of detached housing. ## Ponthir and Torfaen: AdBlue drains across the area Gatlas and Common Cefn-llwyn are among the places near Ponthir, a village, that the same teams cover, over NP postcodes. The van reaches you fastest with a postcode starting NP18 1. The car doesn't need to shift. Wherever it stands — near Ponthir Community Centre, in a layby en route to Ponthir Cricket Pavillion, on a drive — that's where it is drained. Guessing won't help at the back of Farm Shop Ponthir, close to a boundary, or anywhere awkward to describe; ring and check. ## In short, for Ponthir drivers Read the cap before you pour. Even so AdBlue in your diesel tank? Petrol in Diesel will drain it wherever it stands, wherever in Torfaen: keep the car off then ring 0333 366 0103.