--- title: Explained: AdBlue in a Diesel Tank Coryton canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/coryton-cardiff/ location: Coryton county: Cardiff latitude: 51.522090 longitude: -3.231950 service: AdBlue in a Diesel Tank updated: 2026-10-19 --- # AdBlue in a Diesel Tank in Coryton: How It Occurs and How to Stop It AdBlue already in the diesel tank? Then put this page aside a moment, keep the ignition and motor off, and call 0333 366 0103. Around Coryton, finding it before your engine runs normally means draining and a thorough flush where it stands. If you are reading before it has happened, the rest of this page is about why it takes place and how to make sure it does not. ## Why does AdBlue in a diesel car need its own filler? Plenty of current diesels on the roads about Coryton and Rhiwbina carry two liquids, not one. Diesel goes to the engine. Your exhaust, not the motor, is where AdBlue goes: dosed into the fumes to clean it, from a separate tank. Each tank has its own filler. Some vehicles put the AdBlue filler in your boot or under the bonnet; a lot of others have the two side by side under one flap. Diesel goes in at every filling station visit, again and again. A driver who has to stop and work out where it goes normally tops up the AdBlue side, from a bottle, and far less regularly. The error lives in that gap. ## AdBlue in the diesel tank around Coryton: how it occurs Rarely is it carelessness: usually three things coincide. Haste comes from the warning. Your car warns you as AdBlue runs low, and an empty tank sends it into limp mode — so the top-up gets done quickly, before work on a drive off Coryton Rise, or heading home in the car park outside The Hollybush Coryton. The old car's cap is where your hand goes — but a hire car, a new motor or a company car puts the fillers elsewhere. That's a second factor: a strange vehicle. A spouted bottle meets no obstacle at a diesel filler no more than at an AdBlue one. So the tip, after begun, carries on. Pantmawr or the heart of Coryton: it takes the same few seconds in both. ## Which filler is for AdBlue, and which for diesel? A couple of seconds is all these take — so run through them before you pour anything, on a drive in Radyr or a forecourt in Coryton. - Where it sits misleads; the cap does not. AdBlue caps are often blue or carry the name "AdBlue" — diesel caps normally don't. - Plenty of cars give AdBlue the smaller neck of the two. - Lift the flap and check for a label — plenty of cars show which belongs in which inlet just there. - Can't find it next to your diesel inlet? Then check below the bonnet or inside the boot — the handbook says where. - Picking up a hire or company car, perhaps at the car park outside the nearest station? Ask whoever drove it last before leaving, not when the light goes on. ## Topping up AdBlue without it reaching your diesel tank The day the light goes on, wherever around Cardiff, follow this routine. - Turn off after you park — flat ground, engine stopped, and not in a rush by Pantmawr Road at the roadside. - Say "AdBlue" out loud as you unscrew the cap, after finding the AdBlue filler and read it. Daft, perhaps, yet it does the trick. - Leave the diesel cap on. If both sit under one flap, check the diesel cap is still closed before you lift the bottle. - Gently is best, through the bottle's own spout, until it is full or the bottle is empty. - Before you start the vehicle, shut the cap and check again that the diesel cap never opened off. Stop there if you find, at step two or three, that you have already poured into the diesel side. Skip stage five entirely. ## AdBlue in your diesel tank already, in Coryton? Short order, then. Top of it: your motor stays off. Do not switch your ignition on; on plenty of diesels that alone runs the fuel pump. Topping up with diesel will not thin it: rather than mixing, AdBlue sinks to the base of the tank, just where fuel is taken from. Ask the attendants to help roll the vehicle clear of the petrol pump if you're at a forecourt — the Asda, the Tesco or somewhere else. If you are on your own driveway around Coryton, leave the car where it is. When the motor has been run by now, stop safely and switch the vehicle off. Come off the M4 — under a mile out of Coryton — at the first junction. A short hop across Coryton is a smaller job than a run towards Cardiff, under 5 miles away, so tell us roughly how far it went. ## Our arrival around Coryton, and what happens next We come to the vehicle wherever it has stopped, whether that is outside the local primary school, close to Whitchurch-Heath Cricket Club or on your own driveway. Those answers settle this work and our quote, so our technicians ask what got in, roughly how much, and if it has run. Nobody heads out until you've heard the price over the phone. Next: a drain, then a thorough flush of the entire 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 does not wash out on its own. The filter cleaned or, if needed, replaced; fresh diesel in; then a check of your vehicle. Then we start the engine and make sure it runs smoothly before leaving. With pumps fine on a busy forecourt and quiet enough to use outside a house at night, most jobs where the motor has not run need roughly half an hour after our engineers are there. The insurer usually wants an engineer's report and the VAT invoice, and you get both once this job is done. Payment comes on the day, with no deposit. It is worth looking at your insurance while we travel to you: misfuelling cover comes with plenty of policies. ## About Coryton and where it is Coryton is a suburban area in Cardiff, situated on the banks of the River Taff at an elevation of around 43 metres. Coryton lies approximately 3.8 miles northwest of Cardiff city centre, within close proximity to nearby places such as Pantmawr, Whitchurch, and Forest Farm. Coryton is characterised by its predominantly semi-detached housing stock, reflecting the typical residential architecture of the region. Coryton has a population of around 3659 residents, contributing to the wider Cardiff urban area. ## AdBlue drains about Coryton, and Cardiff beyond Coryton is a residential suburb, and our vans that cover it also work the towns near it, Whitchurch and Forest Farm among them, across the CF postcode area. Quote a postcode that starts CF14 7, and the van arrives fastest. There's no need to move the car. Anywhere it sits — near Cancer Research Wales Library, in a lay-by en route to Coryton House Garden, on a drive — that is where it is cleared. Awkward to explain, like the back of Whitchurch Hub? Close to a border? Checking is better than assuming, and so phone. ## Coryton people: the short version Always, the cap; then, the pour. If AdBlue has gone in your diesel tank regardless, leave the car off and ring 0333 366 0103. Petrol in Diesel clears it where it sits, anywhere in Cardiff.