--- title: AdBlue in a Diesel Tank Caerau: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/caerau-cardiff/ location: Caerau county: Cardiff latitude: 51.470170 longitude: -3.246980 service: AdBlue in a Diesel Tank updated: 2026-10-21 --- # Preventing AdBlue in a Diesel Tank in Caerau: Why It Happens Keep the motor and ignition off then call 0333 366 0103 now — reading can wait if AdBlue is already in your diesel tank. A drain plus a thorough flush, carried out just where your car stands around Caerau, is normally what it needs if found before your engine runs. If you are reading before it has happened, the rest of this page is about why it occurs and how to make sure it does not. ## Why does AdBlue in a diesel vehicle need its own filler? Plenty of newer diesels in Michaelston-super-Ely, as well as Caerau, run on two fluids; your engine takes only the diesel. Stored in a tank of its own, AdBlue is sprayed into your exhaust stream to clean it. Different tanks, different fillers. Some vehicles put the AdBlue filler in the boot or under the bonnet; plenty of others place both together under one flap. Diesel goes in at every forecourt call-out, week in, week out. Far less commonly, the AdBlue side gets filled — mostly from a bottle, by someone thinking about where it goes. It's in the gap that the error happens. ## How AdBlue in your diesel tank happens in Caerau It is hardly ever carelessness. Three things tend to line up. Haste follows from the warning. The car warns you as AdBlue runs low, and an empty tank puts it into limp mode — so the top-up happens in a rush, before work on a driveway off Tapley Close, or on the way home in the car park at The Home Guard. Then the car is new. A hire car, a new vehicle or a company car puts the fillers where your last one didn't, and the hand gets to for the cap it would have used on the old one. A spout-topped bottle meets no obstacle at a diesel filler no more than at an AdBlue one. And so the tip, after started, keeps on. It takes a few seconds, whether in Culverhouse Cross or right in the heart of Caerau. ## Which filler is for AdBlue, and which for diesel? Check these before pouring, on a forecourt in Caerau or a driveway over in Wallston. Seconds, that's all. - Check the cap instead of going by position: AdBlue ones are commonly blue or marked "AdBlue", and diesel ones usually are not. - The size. On many cars the AdBlue filler neck is the smaller of the two. - A label inside your fuel flap often shows which fuel goes where, on many motors. Look for it. - The handbook says where it lives when your filler isn't next to the diesel cap: your boot, or under the bonnet. - Check with the person who drove it last — before you leave, not when the light comes on — if you collect a hire or company car from somewhere like the car park outside Waun-Gron Park. ## Keeping AdBlue out of the diesel tank when you top up A routine for the day the light comes on, wherever across Cardiff that is. - Turn off once parked — flat ground, engine stopped, and not rushed beside Church Road on the verge. - Silly as it sounds, speaking "AdBlue" aloud while you unscrew the cap works — after you've located the filler and read it. - Both under a single flap? Then make sure the lid on the diesel filler stays closed before raising the bottle. - Tip slowly, using the bottle's own spout. Stop when it's full or when the bottle is empty. - Only then, start your car: close the cap, check again, and make sure your diesel cap was never opened. Stop there if you find, at step two or three, that you've already poured into the diesel side. Don't carry on to step five. ## AdBlue in your diesel tank already, around Caerau? Do not start your motor: that's how the short order of things begins. On plenty of diesels the ignition alone runs the fuel pump, so do not switch the car on. Filling up with diesel will not weaken it: rather than mixing, AdBlue sinks to the bottom of your tank, just where fuel is taken from. Ask the attendants to help push the vehicle clear of the petrol pump if you are on a forecourt — the Tesco, the Esso or anywhere else. If you are on your own driveway around Caerau, leave it where it stands. Where your motor has run by now, stop somewhere safe and switch it off. The next exit is the place to come off when you are on the M4, under 5 miles from Caerau. About how far did it go? Crossing Caerau is smaller a job than a trip of under 5 miles towards Cardiff, and so tell us. ## What occurs when our technicians arrive around Caerau By the local primary school, near Hill fort or on your own driveway: wherever the vehicle has stopped, our engineers come to it. Those replies decide this work and our quote, so we ask what went in, roughly how much, and if it has run. You hear that price on the phone, before anybody sets off. Emptying your tank comes next, then a full flush of your system. 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 that matters more with AdBlue than with petrol. The fuel filter is flushed, or replaced where it needs to be; clean diesel goes in; and the car is tested. The engine is fired up next and tested to confirm it runs properly, all before we head off. Most jobs are finished in roughly half an hour once our technicians get there, as long as the motor has not run — and the pumps we use are fine on a busy forecourt yet quiet at night beside a house. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. It is worth checking your insurance as the van travels to you: misfuelling cover comes with plenty of policies. ## About Caerau Caerau is a suburban area in Cardiff, situated near the River Ely and close to the city centre. Caerau sits at an elevation of 31 metres, with semi-detached housing being the predominant type of accommodation. Caerau is located near several other suburban areas, including Culverhouse Cross, Cyntwell, and Ely, and is approximately 3.1 miles from Cardiff city centre. ## AdBlue drains across Cardiff, Caerau included Caerau is a residential suburb, and the teams that cover it also work the places near it, Cyntwell and Ely among them, across the CF postcode area. A postcode starting CF5 5 gets our van to you fastest. No need to shift the car. A driveway, a lay-by on the way to Caerau Wood, a side street near St Mary's Church: our engineers drain it where it is. Guessing doesn't help at the back of Caerau Hillfort, on a border, or somewhere hard to describe; phone and ask. ## For Caerau drivers, the short version Tip no AdBlue till you've read the cap. If AdBlue has gone in your diesel tank anyway, leave the vehicle off then phone 0333 366 0103. Petrol in Diesel empties it where it stands, anywhere in Cardiff.