--- title: Explained: AdBlue in a Diesel Tank Maesycoed canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/maesycoed-rhondda-cynon-taf/ location: Maesycoed county: Rhondda Cynon Taf latitude: 51.597640 longitude: -3.351850 service: AdBlue in a Diesel Tank updated: 2026-10-11 --- # Maesycoed: How Does AdBlue End Up in a Diesel Tank, and How Do You Prevent It? Pause reading a minute if your diesel tank already has AdBlue in it: ignition off, motor off, then phone 0333 366 0103. Caught before your engine runs, it is generally a drain and a thorough flush, done where the vehicle is around Maesycoed. Reading in advance? Then the rest explains why it comes about and what to stop it ever happening. ## Two fillers, two tanks: AdBlue in a diesel motor Diesel feeds your engine — yet plenty of newer diesels driven about Maesycoed and Graigwen hold a second liquid too. 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 each tank. Under one flap, next to each other: that is the layout on a lot of vehicles. Elsewhere, AdBlue's filler sits beneath the bonnet or in your boot instead. At the pump, the diesel side is topped up constantly. Someone who has to stop and think where it goes normally fills the AdBlue side, from a bottle, and much less regularly. It's in that gap that the mistake lives. ## AdBlue in the diesel tank in Maesycoed: how it takes place Carelessness rarely causes it. What does is three things coming up at once. To start with, the warning. Low AdBlue brings a message from the car, and letting it run dry leads to limp mode — so a hurried top-up, maybe before work off Gelliwion Woods, perhaps outside The Merlin on the way home after work. Then the car is new. A hire car, a new vehicle or a company car puts the fillers where your last one did not, and your hand gets to for the cap it would have used on the old one. Nothing halts the tip once it has started, because a bottle with a spout goes into a diesel filler as readily as an AdBlue one. The bottle fits. It takes seconds, whether out in Graig or right in the heart of Maesycoed. ## How to tell the AdBlue filler from the diesel one Be it a Maesycoed forecourt or a driveway over in Penygraigwen, take a few seconds on these before anything is poured in. - Position can mislead; the cap does not. AdBlue ones tend to be blue or carry the name "AdBlue" — diesel caps usually don't. - Look at the size: the smaller neck is, on many motors, the AdBlue one. - A label inside your fuel flap often shows which fuel goes where, on plenty of vehicles. Look for it. - The handbook. If the filler isn't by the diesel cap, it's in your boot or under the bonnet, and the handbook says which. - The previous driver knows. Check as you pick up a hire car or company car — from Pontypridd's car park, perhaps — not once the light appears. ## Keeping AdBlue out of the diesel tank when you top up For the day the warning comes on — anywhere you are in Rhondda Cynon Taf — a routine to follow. - Turn off after you park — flat ground, engine stopped, and never in a rush by Llanfair Road on the verge. - Locate the AdBlue filler, check the cap, and speak the word "AdBlue" aloud as unscrewing it. It sounds silly. It works. - Leave the diesel cap on. If both sit under one flap, check your diesel cap is still closed before you lift the bottle. - Using the bottle's own spout, pour slowly — and stop when it is full or the bottle is empty. - Only then, start the car: close the cap, check once more, and make sure your diesel cap was never opened. If at step two or three you find you have already poured into your diesel side, stop there. Skip stage five entirely. ## Maesycoed: already put AdBlue in your diesel tank? What follows is a short order of things, beginning with not starting the motor. On many diesels the ignition alone runs the fuel pump, and so don't switch the vehicle on. Thinning it with more diesel won't work, because AdBlue sinks to the base instead of blending — and that is where your fuel is drawn from. The staff at Asda, Sainsbury's or another forecourt will usually lend a hand pushing your car away when you ask. Leave it where it is if you're on your own driveway around Maesycoed. Stop as soon as it is safe then switch off, if your engine has already run. Come off the M4 — under 10 miles out of Maesycoed — at the next exit. Distance counts — a short hop across Maesycoed is a smaller job than driving under 15 miles to Cardiff — so tell us roughly how far it went. ## Maesycoed: what happens when our engineers get there Our technicians come to the car wherever it has stopped, whether that's outside the local primary school, near Pontypridd RFC or on your own driveway. Which fluid went in, the quantity, and whether it ran: we ask since the answers decide both work and price. On the call itself, you hear the quote — ahead of anything else. The fuel system is then flushed thoroughly, once that tank is cleared. AdBlue crystallises and is corrosive to some of the metals in a fuel system, so it does not wash out on its own — which is why the flush counts more here than with petrol. A test is at the end: before that, fresh diesel is added, and the fuel filter is flushed or changed if necessary. Before we go, we start it and make sure that it is running properly. Unstarted vehicles usually need a half-hour visit from the moment we arrive. The equipment is fine on a busy forecourt, and hushed enough for a residential street after dark. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. It is worth looking at your policy as the van travels to you: misfuelling cover is included with plenty of policies. ## About Maesycoed itself Maesycoed is a suburban area in Rhondda Cynon Taf, situated near the River Taff and close to the nearby towns of Pontypridd and Graig. Maesycoed has a mix of housing types, but is predominantly characterised by terraced homes. Maesycoed sits at an elevation of 117 metres, within commuting distance of Cardiff, the capital city of Wales. ## AdBlue drains about Maesycoed, and Rhondda Cynon Taf beyond Maesycoed is a residential suburb, and the teams that cover it also work the places around it, Pwll-Gwaun and Pontypridd among them, across the CF postcode area. Fastest of all: quote a CF37 1 postcode to our van. Your car remains put. Our technicians drain it where it is — a side street close to Temple Baptist, Graig Building, a lay-by on the way to Ynysangharad Park, a drive. If you're near a boundary, or somewhere hard to describe like the back of Pontypridd Magistrates Court, ring and ask rather than assuming. ## In short, for Maesycoed drivers Before you tip, read the cap. If AdBlue has gone in your diesel tank anyway, leave the car off then phone 0333 366 0103. Petrol in Diesel clears it where it waits, anywhere around Rhondda Cynon Taf.