--- title: Explained: AdBlue in a Diesel Tank Trenoweth canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/trenoweth-cornwall/ location: Trenoweth county: Cornwall latitude: 50.159170 longitude: -5.140150 service: AdBlue in a Diesel Tank updated: 2026-10-11 --- # Why It Occurs and How to Avoid It: AdBlue in a Diesel Tank in Trenoweth Stop here for a moment when your diesel tank already holds AdBlue in it: ignition off, engine off, and call 0333 366 0103. A drain and a full flush, done just where the car sits around Trenoweth, is normally all it needs if found before your motor runs. Nothing happened yet? Below, the rest of the page covers the reasons it takes place and the how to avoid it for good. ## AdBlue in a diesel vehicle, and its separate tank Not one fluid but two: that's how plenty of newer diesels near Trenoweth and Halvosso carry, with diesel for your motor. AdBlue goes to your exhaust, where it is sprayed into the gas to clean it, and it lives in a tank of its own. Each tank has its own filler. Other motors keep the AdBlue filler in the boot or under the bonnet; a lot of others place the two together behind one flap. The diesel side is topped up at the petrol pump all the time. The AdBlue side is fuelled far less commonly, usually from a bottle, and normally by somebody who has to stop and think where it goes. The mistake grows in the gap between them. ## Trenoweth: how AdBlue in the diesel tank takes place Seldom is it carelessness: normally three things line up. On a driveway off Penwarne Road before work, or in the car park outside New Inn at Mabe Cornwall heading home: that's where the hurried top-up happens. What is the reason for the rush? As AdBlue runs low the car warns you, and once it is empty, limp mode kicks in. Then the vehicle is new. A hire car, a new vehicle or a company car puts the fillers where your last one did not, and your hand gets to for the cap it would have used on the old one. A spouted bottle finds no resistance at a diesel filler no more than at an AdBlue one. And so the pour, once begun, carries on. Antron or the heart of Trenoweth: it takes the same few seconds in both. ## Which filler is for AdBlue, and which for diesel? Check these first, on a forecourt around Trenoweth or a driveway over in Lamanva. Seconds, that's all. - Position can mislead; the cap doesn't. AdBlue ones are often blue or bear the word "AdBlue" — diesel caps normally do not. - On plenty of vehicles, size gives it away: AdBlue gets the smaller filler neck. - A label inside your fuel flap frequently says which fuel goes where, on many motors. Look for it. - The handbook. If the filler is not by your diesel cap, it's in your boot or under the bonnet, and the handbook says which. - Picking up a hire or company car, perhaps at the car park outside Penryn? Ask whoever drove it last before you set off, rather than when the light goes on. ## Keeping AdBlue out of your diesel tank when you top up Wherever around Cornwall the light comes on, this is a routine for the day. - Park and switch off. Not on a slope, not with your engine running, and not in a rush on the side of Church Road. - 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 two behind one flap? Then confirm the cap on your diesel filler is still closed ahead of raising the bottle. - Using the bottle's own spout, tip slowly — and stop when it is full or the bottle is empty. - Only after that, start the vehicle: close the cap, check a second time, and make sure the diesel cap was never opened. Stop there if you find, at step two or three, that you've already poured into your diesel side. Do not go on to stage five. ## Trenoweth: already put AdBlue in the diesel tank? Short order, then. Top of it: your motor remains off. Leave your ignition off too, since on many diesels switching it on alone runs your fuel pump. Don't top up with diesel to dilute it: AdBlue does not mix with diesel, it sinks to the bottom of your tank, where the fuel is drawn from. The attendants at Asda, Gulf or another forecourt will normally lend a hand pushing your car clear when you ask. Your own drive in Trenoweth is where it stays. If your engine has already run, stop as soon as it is safe and switch off. On the M5, over 50 miles from Trenoweth, that means the next junction. About how far did it go? Crossing Trenoweth is smaller a job than a run of under 10 miles to Truro, so tell us. ## Our arrival around Trenoweth, and what happens next Outside Mabe Community Primary School, close to St Laud or on your own drive: wherever the car has stopped, we come to it. Those replies settle the work and our quote, so our technicians ask what was put in, about how much, and whether it has run. You hear that price on the phone, before anyone heads out. The system is then cleaned thoroughly, after the tank is drained. More than with petrol, it counts with AdBlue: crystals form, some metals corrode, and nothing clears away on its own, no matter how long it is left. Once your filter is cleaned — or renewed, if required — fresh diesel is added, and then the vehicle gets tested. Next our technicians start the engine and make sure it runs properly before leaving. Most jobs are finished in about half an hour after our engineers arrive, as long as the engine hasn't run — and the pumps our engineers use are safe on a live forecourt yet quiet after dark outside a house. Payment happens on the day, not upfront, and you receive the paperwork an insurer wants: an engineer's report and a VAT invoice. Before we get there, have a look at your policy; many carry cover for misfuelling. ## About Trenoweth Trenoweth is a small hamlet in Cornwall, situated inland at an elevation of around 152 metres, and is located approximately 8 miles from the city of Truro. Trenoweth is characterized by its predominantly detached housing and is surrounded by nearby places such as Antron, Mabe Burnthouse, and Longdowns. Trenoweth has a relatively small population of around 2717 residents, and is a considerable distance from London, at around 237 miles away. ## Trenoweth and Cornwall: AdBlue drains across the area As a rural hamlet, Trenoweth has the same vans as surrounding places — Mabe Burnthouse, Longdowns — all the way across TR postcodes and the wider area around them. A postcode starting TR10 9 gets the van to you fastest. Shifting your car is not necessary. Wherever it sits — near Flexsi Sports Centre, in a lay-by en route to St Gluvias Cricket Club, at home — that is where it is emptied. Tricky to explain, like the back of Treverva Village Hall? Close to a county line? Checking is better than assuming, so ring. ## In short, for Trenoweth people Before you pour, read the cap. If AdBlue has gone in the diesel tank all the same, leave the vehicle off and ring 0333 366 0103. Petrol in Diesel clears it where it stands, anywhere across Cornwall.