--- title: Nant-y-Felin: AdBlue in a Diesel Tank, Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/nant-y-felin-conwy/ location: Nant-y-Felin county: Conwy latitude: 53.248560 longitude: -3.971170 service: AdBlue in a Diesel Tank updated: 2026-10-28 --- # Why It Happens and How to Avoid It: AdBlue in a Diesel Tank in Nant-y-Felin If AdBlue is already in your diesel tank, stop reading for a moment: leave your engine and the ignition off then call 0333 366 0103. In Nant-y-Felin, catching it before the engine runs usually leaves a drain and a thorough flush where it stands. Reading before the event? In that case what follows explains how it comes about and what to prevent it ever happening. ## Two fillers, two tanks: AdBlue in a diesel car Not one fluid but two: that's what many modern diesels around Nant-y-Felin and Penmaen Park run, with diesel for your engine. AdBlue goes to the exhaust, where it is sprayed into the gas to fresh it, and it lives in a tank of its own. Each tank comes with a filler of its own. On a lot of vehicles 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 petrol pump, the diesel side gets filled constantly. A driver who has to stop and think where it goes usually tops up the AdBlue side, from a bottle, and much less often. That gap is where the error lives. ## How does AdBlue in the diesel tank take place in Nant-y-Felin? Carelessness rarely causes it. Instead is three things lining up together. Haste comes from the warning. The vehicle warns you as AdBlue runs low, and an empty tank sends the vehicle into limp mode — so the top-up happens quickly, before work on a drive off Nant Y Felin Road, or on the way home in the car park at Llanfair Arms. Unfamiliar motors come second, as well. Rentals, new vehicles and company motors put their fillers in new places, and habit reaches for the cap 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, and so nothing stops the pour once it has started. Whether it happens in Nant-y-Pandy or the middle of Nant-y-Felin, it's the same few seconds. ## Which filler is for AdBlue, and which for diesel? Look at these before pouring, at a forecourt in Nant-y-Felin or a drive over in Gorddinog. A few seconds, that's all. - Colour and lettering: an AdBlue cap is commonly blue, or says "AdBlue", where a diesel cap usually does not. Trust the cap, not its position. - The size. On plenty of motors the AdBlue filler neck is the smaller of the two. - Lift the flap and check for a label — many cars mark what goes in which inlet right there. - In your boot or under the bonnet: that is where the filler is if it's not by the diesel cap, and the handbook says which. - The previous driver knows. Ask when you collect a hire car or company car — at Llanfairfechan's car park, perhaps — not when the light appears. ## Topping up AdBlue without it reaching your diesel tank A routine for the day the light comes on, wherever in Conwy that is. - Park and switch off. Not on a slope, not with your motor running, and not in a rush on the side of Cân yr Afon. - Say "AdBlue" out loud as you unscrew the cap, after you find the AdBlue filler and read it. Silly, perhaps, but it does the trick. - The two under a single flap? So make sure the lid on the diesel filler is still shut ahead of raising the bottle. - Tip slowly, using the bottle's own spout. Stop when it is full or when the bottle is empty. - Close the cap and check a second time. Make sure the diesel cap was never opened. Only then start the vehicle. Discover at the second or third step that AdBlue went into the wrong filler? That's where you stop. Never go on to step five. ## Already put AdBlue in your diesel tank around Nant-y-Felin? Then the order of things is short. Don't start your engine. The fuel pump starts on many diesels the moment your ignition is switched on — and so keep it off. Filling up with diesel will not dilute it: instead, AdBlue drops to the base of that tank, right where fuel is taken from. If you are on a forecourt, whether it is the Shell or the another forecourt nearby, ask the attendants to help roll the car clear of the petrol pump. On your own drive around Nant-y-Felin? Then your car stays where it is. When the engine has been run already, pull over safely and switch the car off. Nant-y-Felin sits under 50 miles from the Moreton Spur; on it, take the first exit. Roughly how far did it go? Crossing Nant-y-Felin is less a job than a run of under 10 miles to Bangor, so tell us. ## What happens when we turn up around Nant-y-Felin Wherever the vehicle has stopped, whether outside the local primary school, near St Mary of the Angels or on your own drive, our van travels to it. Both the work and the quote rest on three answers — which liquid, which quantity, and if it has run — so our engineers ask. That price is given over the phone, before any van leaves. The fuel system is then purged thoroughly, once your tank is emptied. Unlike petrol, AdBlue forms crystals and eats at some fuel-system metals, and neither clears out by itself. Hence it matters more. Filter cleaned or, if it must be, swapped; fresh diesel in; and then a test of the vehicle. After that our engineers start the engine and confirm it runs properly before we leave. Unstarted vehicles mostly mean a half-hour job after arrival. The kit is safe on a busy forecourt, and hushed enough for a driveway after dark. Nothing in advance; you settle up that day. At the end, a VAT invoice and the report from the engineer are handed to you for your insurer. Many insurance policies include misfuelling cover, so it is worth checking yours while we are on the way. ## About Nant-y-Felin and where it is Nant-y-Felin is a suburban area in Conwy, situated on the north Welsh coast, with Nant-y-Felin being close to the nearby towns of Llanfairfechan and Bangor. Nant-y-Felin has a population of around 2263 people, with Nant-y-Felin predominantly consisting of semi-detached housing. Nant-y-Felin is located at an elevation of 72 metres, with Nant-y-Felin sitting near the communities of Nant-y-Pandy and Pentre Uchaf. ## Nant-y-Felin and Conwy: AdBlue drains across the area Pentre Uchaf and Llanfairfechan are among the towns near Nant-y-Felin, a residential suburb, that the same vans cover, over LL postcodes. Quote a postcode that starts LL33 0, and the van arrives fastest. Shifting the vehicle is not necessary. Our engineers drain it where it is — a side street near Llanfairfechan Library, a lay-by on the way to Llys-y-gwynt Covert, a drive. If you are close to a boundary, or somewhere hard to explain like the back of Llanfairfechan Community Hall, ring and ask instead of guessing. ## The short version for Nant-y-Felin people Before you tip, read the cap. AdBlue in your diesel tank after all? Keep the car switched off then call 0333 366 0103; Petrol in Diesel drains it where it stands, across Conwy.