--- title: Explained: AdBlue in a Diesel Tank Cotham canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/cotham-bristol/ location: Cotham county: Bristol latitude: 51.464470 longitude: -2.596410 service: AdBlue in a Diesel Tank updated: 2026-10-14 --- # Why It Happens and How to Avoid It: AdBlue in a Diesel Tank in Cotham If AdBlue is already in your diesel tank, stop reading for a moment: leave the engine and your ignition off then phone 0333 366 0103. A drain plus a thorough flush, carried out right where your vehicle stands in Cotham, is usually all it needs when found before your engine runs. The rest of this page explains why it occurs and how to make sure it doesn't — handy if you are reading before it has happened. ## Why does AdBlue in a diesel vehicle need its own filler? Many modern diesels in Montpelier, as well as Cotham, run on two liquids; your engine gets only the 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. Each tank has its own filler. Under one flap, next to each other: that is the arrangement on a lot of vehicles. Elsewhere, AdBlue's filler is under the bonnet or in your boot instead. At the petrol pump, your diesel side is topped up constantly. The AdBlue side is fuelled far less often, usually from a bottle, and usually by someone who has to stop and think where it goes. That gap is where the slip lives. ## How does AdBlue in the diesel tank happen around Cotham? Three things tend to line up, and carelessness is rarely one of them. Haste comes from the warning. The vehicle tells you as AdBlue runs low, and an empty tank sends it into limp mode — so the top-up happens quickly, before work on a drive off Cotham Side, or heading home in the car park outside Cotham Porter Stores. Then your car is unfamiliar. A hire car, a new car or a company car puts the fillers where your last one did not, and your hand hits for the cap it would have used on the old one. A spouted bottle meets no obstacle at a diesel filler any more than at an AdBlue one. And so the pour, once started, keeps on. It takes a few seconds, whether out in Kingsdown or right in the heart of Cotham. ## Telling the AdBlue filler from the diesel filler A few seconds is all these take — so check them before you tip anything, on a driveway in Victoria Park or a forecourt around Cotham. - Read the cap instead of going by where it sits: AdBlue caps are frequently blue or marked "AdBlue", and diesel caps normally aren't. - Plenty of cars fit AdBlue the smaller filler of the two. - Open the flap and check for a label — many vehicles mark which belongs in which filler right there. - The handbook shows which it lives if your filler isn't next to your diesel cap: the boot, or under the bonnet. - Collecting a hire or company car, perhaps at the car park outside Redland? Ask whoever drove the car last before leaving, rather than once the light goes on. ## AdBlue top-ups that never reach your diesel tank The day the light goes on, anywhere across Bristol, follow this routine. - Stop somewhere level, engine off, with time in hand — not hurried on the side of Cotham Brow. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds daft and it does the trick. - The diesel cap remains on. When both share a flap, confirm it's shut before lifting the bottle. - Using the bottle's own spout, tip slowly — and stop when it is full or the bottle is empty. - Close the cap, then check once more — confirm the diesel filler stayed closed throughout. After that, start the vehicle. Spot at step two or three that it's already gone into your diesel side? Then stop just there. Don't go on to step five. ## Cotham: already put AdBlue in the diesel tank? What follows is a short order of things, beginning with not starting the motor. On many diesels your ignition alone runs the fuel pump, so do not switch it on. AdBlue doesn't mix with diesel — it sinks to the bottom of your tank, where your fuel is pulled from — so do not top up with diesel to dilute it. If you're at a forecourt, whether it is the Esso or the Shell, ask the attendants to help roll the vehicle away from the petrol pump. If you are on your own driveway around Cotham, leave the vehicle where it sits. Stop as soon as it is safe and switch off, if your engine has already run. On the M32, under a mile from Cotham, that means the next junction. Roughly how far did it go? Crossing Cotham is smaller a job than a trip of under a mile to Bristol, and so tell us. ## Our arrival around Cotham, and what happens next Anywhere your car came to rest, be it outside Cotham Gardens Primary School, near St. Matthew's Church or at home, our van travels to it. What liquid got in, the quantity, and if it ran: we ask because those answers decide the work and price. The quote is given over the phone, ahead of any van leaving. The system is then rinsed thoroughly, once that tank is emptied. Not like petrol, AdBlue forms crystals and eats at some fuel-system metals, and none of that washes out by itself. That is why it counts more. Filter cleaned or, where it must be, replaced; clean diesel in; and then a check of the vehicle. The motor is started next and checked to be sure it runs correctly, all before our engineers head off. Using pumps fine on a working forecourt and quiet enough to use outside a house at night, most jobs where your motor has not run need about half an hour after our engineers arrive. Your insurer usually wants an engineer's report and your VAT invoice, and both are yours once this job is done. Payment comes on the day, with no deposit. Before we get there, have a look at your insurance documents; plenty include cover for misfuelling. ## About Cotham, briefly Cotham is a suburban area in Bristol, situated approximately 0.8 miles from the city centre, with a mix of old and new buildings, including a high proportion of flats. Cotham sits at an elevation of around 66 metres, in a location that is relatively flat compared to some other areas of Bristol. Cotham is close to nearby places such as Kingsdown, Tyndalls Park, and Redland, and is home to a population of around 17008 people. Cotham is also within easy reach of the wider South West region, being around 106.2 miles from London. ## AdBlue drains about Cotham, and Bristol beyond Cotham is a residential suburb, and our vans that cover it also work the towns near it, Tyndalls Park and Redland among them, across the BS postcode area. The van reaches you fastest with a postcode starting BS6 6. Your car stays put. A drive, a lay-by on the way to Fremantle Square, a side street close to Muller House: our technicians drain it where it sits. Ring and ask instead of guessing if you are close to a border, or somewhere hard to describe, like the back of Robert Sothey. ## Cotham people: the short version Read the cap before you pour. AdBlue in your diesel tank regardless? Keep the vehicle off and phone 0333 366 0103; Petrol in Diesel empties it on the spot, across Bristol.