Why It Happens and How to Prevent It: AdBlue in a Diesel Tank in Cardiff
If AdBlue is already in your diesel tank, stop reading for a moment: leave your motor and the ignition off then ring 0333 366 0103. Around Cardiff, 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 remainder of this page is about why it happens and how to make sure it does not.
Two fillers, two tanks: AdBlue in a diesel car
Plenty of modern diesels in Riverside, like those in Cardiff, carry on two liquids; your motor gets just your diesel. AdBlue goes to your exhaust, where it is sprayed into the gas to fresh it, and it lives in a tank of its own.
Every tank has one filler of its own. 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. The diesel side is topped up at the pump all the time. Rarely topped up, AdBlue normally goes in out of a bottle, tipped by a driver who has to stop and think what cap to use. The mistake lives in that gap.
How AdBlue in the diesel tank occurs around Cardiff
Seldom is it carelessness: normally three things line up.
First, the warning. Low AdBlue brings a warning from the vehicle, and running out leads to limp mode — so a rushed top-up, perhaps before work off The Hayes, perhaps at The Glassworks on the way home that evening.
New-to-you cars are next, as well. Rentals, new cars and company cars place their fillers differently, and habit goes 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 occurs in Central or the middle of Cardiff, it is the same few seconds.
Telling the AdBlue filler from the diesel filler
Look at these first, at a forecourt in Cardiff or a drive over in Butetown. Seconds, no more.
- The cap. The AdBlue cap is commonly blue, or marked "AdBlue". The diesel cap usually isn't. Read it instead of going by position.
- Plenty of vehicles fit AdBlue the smaller filler of the two.
- Open the flap and check for a label — many vehicles show what goes in which filler just there.
- The handbook. If your filler isn't by your diesel cap, it is in the boot or under the bonnet, and the handbook says which.
- The person who drove the car last. On a hire or company car picked up from somewhere like the car park outside Cardiff Queen Street, ask before you leave, not when the light comes on.
How to top up without AdBlue in your diesel tank
A routine for the day the light comes on, wherever around Cardiff that is.
- Not in a rush on the side of Working Street, not on a slope, not with your engine running: park and switch off properly.
- Say "AdBlue" out loud as you unscrew the cap, after you find the AdBlue filler and reading it. Silly, yes, but it does the trick.
- Leave your diesel cap on. If both sit under one flap, check the diesel cap is still closed before you lift the bottle.
- Using the bottle's own spout, tip slowly — and stop when it is full or the bottle is empty.
- Close the cap and check again. Make sure the diesel cap was never opened. Only then start the car.
If at stage two or three you find you have already poured into the diesel side, stop there. Do not go on to step five.
Put AdBlue in your diesel tank in Cardiff already?
Do not start your engine: that is where the short order of things begins. Leave your ignition off as well, since on plenty of diesels it alone runs your fuel pump. Don't top up with diesel to thin it: AdBlue doesn't mix with diesel, it sinks to the bottom of that tank, where your fuel is pulled from.
If you're on a forecourt, whether it's the Texaco or the Esso, ask the attendants to help roll your car away from the pump. Leave it where it is if you're on your own drive around Cardiff.
If your engine has already run, stop as soon as it is safe and switch off. Come off the M4 — under 5 miles out of Cardiff — at the next junction. A short hop across Cardiff is a smaller job than a run towards Newport, under 15 miles away, and so tell us about how far it went.
Cardiff: what happens when our technicians get there
Our technicians come to the car wherever it has stopped, whether that's outside the local primary school, near Cardiff Story Museum or on your own drive. Both the work and our price depend on three replies — what fluid, which quantity, and whether it has run — so our engineers ask. Nobody sets off until you've heard our quote by phone.
Your system is then rinsed thoroughly, once the tank is emptied. 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 counts more with AdBlue than with petrol. Testing comes at the end: before that, fresh diesel goes in, and the filter is cleaned or replaced if necessary. We do not leave until it has been fired up and is running properly.
Most jobs are done in roughly half an hour after our engineers get there, provided the engine hasn't run — and the pumps our technicians use are safe on a live forecourt and quiet at night outside a house. No money in advance; you settle up that day. Afterwards, a VAT invoice and a report from the engineer are handed to you for the insurer. Many insurance policies include misfuelling cover, so it's worth checking yours whilst we're on the way.
About Cardiff, for a moment
Cardiff is a major city situated on the coast of southeast Wales, serving as the country's capital. It has a long history of growth, transforming from a small town to a significant urban centre, largely due to its role as a key port for the coal mining industry. Cardiff is nestled within the historic county of Glamorgan and is part of a larger urban area that extends beyond its boundaries. The city's strategic location and rich history have contributed to its importance in the region.
Cardiff and Cardiff: AdBlue drains across the area
Over CF postcodes, our teams that cover Cardiff — a capital city — work the nearby locations too, Adamsdown and Cathays Park included. A postcode starting CF10 1 gets our van to you fastest.
The vehicle remains put. We drain it where it is — a side street close to Saint David's Hall, a lay-by on the way to St. John’s Gardens, a drive. If you're close to a boundary, or somewhere hard to explain like the back of Batchelor Monument, ring and ask rather than assuming.
The short version for Cardiff people
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 drains it where it sits, anywhere across Cardiff.