--- title: Explained: AdBlue in a Diesel Tank Knowle canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/knowle-bristol/ location: Knowle county: Bristol latitude: 51.438160 longitude: -2.575230 service: AdBlue in a Diesel Tank updated: 2026-10-18 --- # Knowle: How Does AdBlue End Up in a Diesel Tank, and How Do You Prevent It? Pause reading for a moment when your diesel tank already holds AdBlue in it: ignition off, motor off, and call 0333 366 0103. Around Knowle, catching it before the engine turns usually leaves a drain and a full flush on the spot. Here in advance? Then what follows covers how it happens and what to stop it happening at all. ## Why does AdBlue in a diesel motor need its own filler? Not one fluid but two: that's what many modern diesels near Knowle and Upper Knowle run, with diesel feeding the engine. The exhaust, not the motor, is where AdBlue goes: sprayed into the gas to fresh them, from a separate tank. Every tank comes with one filler of its own. Under one flap, next to each other: that is the arrangement on many motors. On others, AdBlue's filler sits beneath the bonnet or in your boot instead. Diesel goes in at each forecourt visit, week in, week out. Rarely filled, AdBlue normally comes from a bottle, poured by a driver who must stop and think what cap it needs. The mistake lives in that gap. ## How does AdBlue in your diesel tank happen in Knowle? Carelessness rarely explains it. Instead is three things lining up at once. Haste follows from the warning. The vehicle tells you as AdBlue runs low, and a dry tank puts the vehicle into limp mode — so the top-up happens quickly, before work on a driveway off Crowndale Road, or heading home in the car park outside The George. The old car's filler is where the hand goes — but a hire car, a new motor or a company car puts the fillers elsewhere. That's a second factor: a strange motor. Lastly, the spout goes in: diesel filler or AdBlue one, it goes in as readily, and after the pour begins, no part stops it. Whether it happens in Totterdown or the middle of Knowle, it is the same few seconds. ## The AdBlue filler and the diesel filler: telling them apart Before you tip anything, whether on a drive in Arnos Vale or a forecourt in Knowle, check these. They take a few seconds. - Blue and marking: an AdBlue cap is regularly blue, or says "AdBlue", where a diesel cap normally doesn't. Trust the cap, not where it sits. - Check the size: the smaller neck is, on plenty of cars, the AdBlue one. - The flap. Look inside the fuel flap for a label. Many motors say there which fuel goes where. - In your boot or under the bonnet: that's where your filler is if it is not by the diesel cap, and the handbook tells you which. - The person who drove it last. On a hire or company car collected from somewhere like the car park at Bristol Temple Meads, ask before you leave, not when the light comes on. ## Topping up AdBlue without it reaching your diesel tank For the day the warning appears — wherever it is around Bristol — a routine to use. - Park and switch off. Not on a slope, not with the motor running, and not in a rush on the side of Sylvia Avenue. - Say "AdBlue" out loud as you unscrew the cap, after you find the AdBlue filler and read it. Silly, yes, but it works. - Leave the diesel cap on. If both sit under one flap, check your diesel cap is still closed before you lift the bottle. - Tip slowly, using the bottle's own spout. Stop when it's full or when the bottle is empty. - Only then, start the vehicle: close the cap, check again, and make sure your diesel cap was never opened. Spot at stage two or three that it's already gone into your diesel side? Then stop right there. Step five is off limits. ## Already put AdBlue in your diesel tank around Knowle? Then the order of things is short. Do not start the engine. Don't switch your ignition on; on many diesels that alone runs the fuel pump. Topping up with diesel will not weaken it: instead, AdBlue sinks to the bottom of the tank, just where the fuel is taken from. On a forecourt — Shell, Sainsbury's or any other — the staff will usually help push the vehicle clear, when you ask. Your own drive around Knowle is the place it should stay. When the motor has been run already, pull over somewhere safe and switch it off. Come off the M32 — under 3 miles out of Knowle — at the next junction. Mileage counts — a quick hop across Knowle makes a smaller job than heading under 3 miles to Bristol — so tell us about how far it went. ## Our arrival around Knowle, and what happens next The van reaches your car wherever it has come to rest — your own drive, beside Totterdown Baptist Church, or by Hillcrest Primary School. Which fluid got in, the amount, and whether it ran: our engineers ask since the replies set both work and quote. Nobody heads out before you have had our price by phone. Emptying that tank comes next, then a full flush of your system. More than with petrol, it counts here: crystals build up, certain metals are attacked, and none of that clears away on its own, however long it sits. Testing is last: before that, clean diesel goes in, and the filter is flushed or changed as needed. After that our technicians fire it up and check it runs correctly before we go. Using pumps fine on a working forecourt and quiet enough for use outside a house at night, most jobs where your engine has not run take roughly half an hour after we are there. Nothing in advance; you settle up that day. Afterwards, a VAT invoice and the report from the engineer are handed to you for your insurer. It's worth checking your policy while we travel to you: misfuelling cover comes with plenty of policies. ## About Knowle Knowle is a suburban area in Bristol, situated on the banks of the River Avon at an elevation of around 58 metres. Knowle is characterized by its predominantly terraced housing stock and is located approximately 1.5 miles from the city centre of Bristol. Knowle is close to nearby places such as Totterdown, Windmill Hill, and Knowle Park, and is home to a population of around 11842 people. Knowle is also within easy reach of the wider South West region, being around 105.4 miles from London. ## AdBlue drains across Bristol, Knowle included Over BS postcodes, our vans covering Knowle — a residential suburb — work the surrounding spots too, Knowle Park and Windmill Hill included. A postcode starting BS4 2 gets the van to you fastest. No need to move the vehicle. Draining happens on the spot, whether a driveway, a street near Jarman Hall, or a lay-by on the way to Perrett Park. Ring and ask instead of guessing if you're close to a border, or somewhere hard to describe, like the back of Holy Nativity Church. ## Knowle people: the short version Always, the cap; then, the pour. AdBlue in the diesel tank after all? Keep it switched off and phone 0333 366 0103; Petrol in Diesel empties it on the spot, throughout Bristol.