--- title: AdBlue in a Diesel Tank Cosby? Read This canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/cosby-leicestershire/ location: Cosby county: Leicestershire latitude: 52.549410 longitude: -1.193170 service: AdBlue in a Diesel Tank updated: 2026-10-07 --- # Why It Happens and How to Prevent It: AdBlue in a Diesel Tank in Cosby Stop here a minute when the diesel tank already holds AdBlue in it: ignition off, engine off, and ring 0333 366 0103. Caught before the motor runs, it is normally a drain and a thorough flush, done where the car is in Cosby. The rest of this page covers why it takes place and how to make sure it doesn't — handy if you're reading before it has happened. ## AdBlue in a diesel car: two tanks, two fillers No single liquid but two: that is what many newer diesels near Cosby and Broughton Astley carry, with diesel for your motor. AdBlue goes to the exhaust, where it is sprayed into the gas to fresh it, and it lives in a tank of its own. Different tanks, separate fillers. Plenty of cars have a single flap for the two, while others put the AdBlue filler to the boot or under the bonnet. At the petrol pump, the diesel side is topped up constantly. Much less frequently, the AdBlue side gets filled — mostly from a bottle, by a person working out where it goes. Mistakes happen in that gap between the two. ## How AdBlue in the diesel tank happens in Cosby Three things tend to come together, and carelessness is rarely one of them. On a drive off Bradbury Close before work, or in the car park at Cosby Working Mens Club heading home: that's where the rushed top-up happens. What is the reason for the rush? As AdBlue runs low the vehicle warns you, and if it's empty, limp mode follows. The old car's cap is where the hand reaches — yet a rental car, a new vehicle or a company car puts the fillers somewhere else. That is the second factor: an unfamiliar vehicle. No part stops the pour once it has started, since a bottle with a spout goes into a diesel filler as readily as an AdBlue one. The bottle fits. The same few seconds decide it, in the middle of Cosby or out in Littlethorpe. ## How to tell the AdBlue filler from the diesel one Check these first, at a forecourt in Cosby or a drive over in Sutton in the Elms. A few seconds, no more. - Colour and lettering: an AdBlue cap is often blue, or says "AdBlue", where a diesel cap usually doesn't. Go by the cap, not its position. - The size. On plenty of vehicles the AdBlue filler neck is the smaller of the two. - The flap. Look inside the fuel flap for a label. Many vehicles say there which fuel goes where. - In the boot or under the bonnet: that's where the filler is if it's not by the diesel cap, and the handbook says which. - Collecting a hire or company car, perhaps at the car park at Narborough? Check with the person who drove the vehicle last before leaving, not when the light comes on. ## Keeping AdBlue out of the diesel tank when you top up Anywhere in Leicestershire the light comes on, this is a routine for the day. - Pull in somewhere level, engine off, with time to spare — never hurried on the side of Chiltern Avenue. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds daft and it works. - Leave the diesel cap on. If both sit under one flap, check the diesel cap is still closed before you lift the bottle. - Slowly is best, through the bottle's own spout, till it is full or the bottle runs out. - Only after that, start the car: close the cap, check once more, and make sure your diesel cap was never opened. Stop there if you find, at stage two or three, that you have already poured into the diesel side. Step five is off limits. ## Cosby: already put AdBlue in your diesel tank? Brief order, then. Top of it: your engine stays unstarted. Leave the ignition off as well, because on plenty of diesels it alone starts the pump. Filling up with diesel won't weaken it: instead, AdBlue sinks to the base of the tank, right where the fuel is taken from. On a forecourt — Texaco, Esso or another — the attendants will usually help push your car clear, if you ask. At home in Cosby? So your car stays put. Already run? Pull over when it's safe, then turn off. On the M1, under a mile from Cosby, that means the next junction. A short hop across Cosby is a smaller job than a run towards Leicester, under 10 miles away, and so tell us roughly how far it went. ## What occurs when our engineers get there in Cosby We come to the car wherever it has stopped, whether that's outside Cosby Primary School, close to Bunning Memorial Hall or on your own drive. The replies determine this work and the quote, and so we ask what went in, about how much, and if it has run. You get that price on the phone, before anyone heads out. Draining that tank comes next, then a full flush of your system. More than with petrol, it matters with AdBlue: crystals form, certain metals corrode, and none of that washes away unaided, no matter how long it is left. The filter is cleaned, or replaced where it needs to be; fresh diesel goes in; and the car is tested. Next we fire it up and confirm it runs properly before leaving. Unstarted cars usually mean a half-hour visit from arrival. The kit is fine on a busy filling station, and hushed enough for a residential street after dark. Your insurer usually wants an engineer's report and the VAT invoice, and both are yours once this job is done. Payment comes on the day, with no money upfront. It is worth checking your insurance while we travel to you: misfuelling cover is included with plenty of policies. ## About Cosby Cosby is a village in Leicestershire, situated approximately 6 miles southwest of Leicester, and is characterised by its semi-detached housing stock. Cosby sits in a low-lying area at an elevation of around 77 metres, near the villages of Littlethorpe and Whetstone. Cosby is located near the larger village of Narborough and is about 85 miles northwest of London. Cosby has a population of around 1933 residents. ## AdBlue drains in Cosby and across Leicestershire Whetstone and Narborough are among the places around Cosby, a rural village, that the same teams cover, over LE postcodes. A postcode starting LE9 1 gets the van to you fastest. The car stays put. Our engineers drain it where it is — a side street near St Michael and All Angels, a lay-by on the way to Cosby Golf Club, a drive. If you are close to a boundary, or somewhere hard to describe like the back of Cosby Toc-H, ring and ask instead of guessing. ## The short version for Cosby drivers Pour nothing till you've read the cap. If AdBlue has gone in your diesel tank all the same, leave it off and call 0333 366 0103. Petrol in Diesel empties it where it sits, anywhere in Leicestershire.