--- title: Explained: AdBlue in a Diesel Tank Falmouth canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/falmouth-cornwall/ location: Falmouth county: Cornwall latitude: 50.153490 longitude: -5.074030 service: AdBlue in a Diesel Tank updated: 2026-10-03 --- # Falmouth: How Does AdBlue End Up in a Diesel Tank, and How Do You Prevent It? Keep the engine and ignition off and phone 0333 366 0103 first — the rest can wait when AdBlue is already in your diesel tank. A drain and a thorough flush, carried out just where the vehicle stands in Falmouth, is usually all it needs when found before the motor runs. If you're reading before it has happened, the remainder of this page is about why it happens and how to make sure it does not. ## AdBlue in a diesel car: two tanks, two fillers Many current diesels on the roads round Falmouth and Mongleath carry two liquids, not one. Diesel goes to your motor. AdBlue goes to your exhaust, where it is sprayed into the gas to fresh it, and it lives in a tank of its own. There's a filler on every tank. On a lot of cars the two sit side by side under the same flap; on others the AdBlue filler is in the boot or under the bonnet. At the pump, your diesel side is topped up constantly. A driver who has to stop and work out where it goes usually fills the AdBlue side, from a bottle, and much less frequently. Mistakes happen in the gap between them. ## How does AdBlue in the diesel tank take place around Falmouth? It is seldom carelessness. Three things tend to line up. First, the warning. Low AdBlue triggers a warning from the car, and running out leads to limp mode — hence a hurried top-up, perhaps before work off Killigrew Street, perhaps at The Moth and the Moon on the way home after work. The old car's filler is where the hand reaches — yet a rental car, a new car or a company car puts the fillers somewhere else. That is the second thing: an unfamiliar vehicle. A spouted bottle finds no obstacle at a diesel filler no more than at an AdBlue one. So the tip, after begun, keeps on. The same few seconds settle it, in the middle of Falmouth or out in Swanvale. ## How to tell the AdBlue filler from the diesel one Be it a Falmouth forecourt or a drive over in Tregew, take a few seconds on these before any is poured in. - Where it sits can mislead; the cap does not. AdBlue caps tend to be blue or carry the word "AdBlue" — diesel caps normally do not. - On plenty of cars, the size gives it away: AdBlue gets the smaller filler neck. - 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 tells you which. - The previous driver knows. Ask when you pick up a hire car or fleet car — at Penmere's car park, say — rather than when the warning appears. ## AdBlue top-ups that never reach the diesel tank The day the light comes on, wherever in Cornwall, use this routine. - Turn off once parked — flat ground, engine stopped, and never rushed beside Trelawny Road at the roadside. - Find the AdBlue filler, read the cap, and speak the word "AdBlue" aloud while you unscrew it. It seems silly. It does the trick. - Both under a single flap? Then confirm the lid on the diesel side is still shut before raising the bottle. - Gently is best, through the bottle's own spout, till it's full or the bottle is empty. - Before starting the car, shut the cap and check again that the diesel cap never opened off. If at step two or three you find you have already poured into the diesel side, stop there. Don't go on to stage five. ## AdBlue in the diesel tank already, around Falmouth? Don't start your engine: that is where the short order of things begins. Don't switch the ignition on; on many diesels that alone runs the fuel pump. Don't top up with diesel to dilute it: AdBlue doesn't mix with diesel, it sinks to the bottom of the tank, where the fuel is drawn from. The attendants at Esso, another forecourt nearby or any forecourt will normally lend a hand pushing your car clear when asked. If you're on your own drive around Falmouth, leave it where it sits. When the engine has been run by now, pull over safely then switch it off. Leave the M5 — over 50 miles out of Falmouth — at the first junction. A short hop across Falmouth is a smaller job than a run towards Truro, under 10 miles away, and so tell us about how far it went. ## What occurs when our technicians get there in Falmouth By King Charles Church of England Primary School, close to The Phoenix or on your own drive: wherever the car has stopped, we come to it. Both the work and our price depend on three replies — what liquid, what quantity, and if it's run — so our engineers ask. The quote comes on the call, ahead of any van leaving. Next: draining, then a full flush of the entire system. Much more than with petrol, it counts with AdBlue: the crystals form, some metals corrode, and nothing washes out unaided, no matter how long it sits. Filter cleaned or, where needed, replaced; fresh diesel in; and then a check of your car. Then we fire it up and confirm it runs smoothly before we leave. Most jobs are done in about half an hour after our technicians arrive, as long as your motor hasn't run — and the pumps we use are fine on a live forecourt yet quiet after dark beside a house. Your insurer usually wants an engineer's report and your VAT invoice, and you get both once the job is done. Payment is on the day, with no money upfront. Wrong-fuel cover is included in many insurance policies — and so use the wait to check yours. ## About Falmouth and where it is Falmouth is a coastal town in Cornwall, situated on the southern coast of the county, with a population of around 21415 people. Falmouth sits at an elevation of 22 metres, overlooking the sea and surrounded by nearby places such as Swanvale, Boslowick, and Flushing. Falmouth is characterized by its predominantly terraced housing and is located near the city of Truro, which is approximately 7.7 miles away. Falmouth is also a significant distance from London, at around 235.2 miles. ## AdBlue drains in Falmouth and across Cornwall Boslowick and Flushing are among the places near Falmouth, a coastal town, that the same vans cover, over TR postcodes. A postcode starting TR11 3 gets our van to you fastest. The car stays where it is. Draining takes place on the spot, be it a driveway, a road by The Salvation Army - Falmouth, or a layby towards Kimberley Park. Assuming doesn't help at the back of Falmouth Evangelical Church, on a boundary, or somewhere hard to pin down; ring and ask. ## The short version for Falmouth people Before you pour, read the cap. Still AdBlue in your diesel tank? Petrol in Diesel will drain it wherever it is, wherever in Cornwall: switch the car off then call 0333 366 0103.