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An AdBlue warning or a "no start in X miles" countdown means the emissions system has found a problem, and left alone it ends in a no-start on many vehicles. Call with your reg and the dash message: we triage it by phone, tell you who can attend, agree the price, then repair it properly.
Have your reg, the exact dash message and any fault codes to hand. We'll tell you on the call what it's likely to be and what happens next.
The short answer
- Warning or countdown?
- If the AdBlue is low, add the amount the dash or handbook asks for. If the level was fine, or the warning stays after a top-up and a short drive, it is a fault: book a repair while the vehicle still starts. On many makes it won't restart at zero.
- Who comes out
- Our own technicians in Devon. Elsewhere, a vetted independent technician near you where we have one.
- Cost
- Agreed with you before any repair. Call for a quote for your vehicle.
- What we won't do
- Delete the system, fit an emulator or reset the countdown without a repair.
What the AdBlue system does, in plain words
AdBlue is urea in purified water, made to a set standard (ISO 22241). It is sprayed into the exhaust ahead of the SCR catalyst, which uses it to turn nitrogen oxides (NOx) into nitrogen and water. NOx sensors check that it is working.
If the tank runs low or the system stops working properly, type-approval rules require the vehicle to warn you, then restrict you if it isn't put right. Makes differ: a countdown to a no-start, reduced power or speed, or no restart after the next refuel. The countdown isn't the fault. It is the vehicle telling you something needs fixing.
The faults behind AdBlue warnings
One dash message can come from several different parts, so we prove the fault before quoting for a repair. These are the areas we check:
- NOx sensors. A sensor that reads wrong can make a working system look faulty.
- The dosing injector. It can block with crystallised AdBlue or stick.
- The pump and lines. Leaks, blocked filters or a weak pump show up as low pressure.
- The tank assembly. On some vehicles the pump, heater and level sensor are built into the tank and only sold as one unit.
- Heaters. AdBlue freezes at about minus 11°C, so the tank and lines are heated, and a failed heater circuit sets its own faults.
- Wiring and connectors. Corroded plugs and chafed wiring can look exactly like a failed part.
- The fluid. Contaminated, diluted or wrong fluid in the tank can set quality or efficiency faults.
- The SCR catalyst. Only judged once everything feeding it has been proved good.
Peugeot, Citroen, DS or Vauxhall? Stellantis runs a voluntary support scheme for AdBlue (urea) tank faults on some diesels built between January 2014 and August 2020, with age and mileage limits. Ask a franchised dealer whether yours qualifies before paying anyone, us included.
Fault codes and dash messages
A generic fault code tells you which part of the system the engine computer is unhappy with, not which part has failed. Makes also use their own codes and wording, so treat these as a starting point:
- P20EE, SCR NOx catalyst efficiency below threshold (bank 1). Too little NOx is being removed. We rule out sensors, dosing and fluid before blaming the catalyst.
- P20E8, reductant pressure too low. The cause can be an empty or frozen tank, a leak, a blocked filter or pick-up, or a tired pump.
- P204F, reductant system performance (bank 1). A broad code, so the other stored codes and the live data matter more than the code itself.
Each of these codes, the countdown message and the warning light has its own guide in the list further down this page.
How it works with us
The same steps for one car or a yard full of vans.
- 1
Call, WhatsApp or text
Give us the reg, the exact dash message (a photo is ideal), the miles left on any countdown, any fault codes and where the vehicle is. No codes is fine.
- 2
Phone triage
We ask when it started, about recent top-ups or repairs and what else is on the dash. That narrows down what needs testing.
- 3
We tell you who attends
In Devon, one of our own technicians. Elsewhere, a vetted independent technician if we have one near you. If we can't cover your area, we say so on the call.
- 4
Price agreed before any repair
Nothing is fitted until you have agreed the price. If the fault needs confirming on the vehicle first, we tell you that up front.
- 5
Repair and set-up
We fit the part, then run the teach-in, initialisation or adaptation reset the manufacturer requires. Skip that step and a good new part can still leave the warning on.
- 6
Confirm the fix
We clear the codes, check live NOx and dosing data, and make sure the warning and countdown have gone. Some systems need a drive to finish rechecking.
Coverage: Devon and beyond
In Devon, our own technicians attend from our Totnes workshop. Some repairs are done where the vehicle is and some need a workshop, depending on the fault and where the part sits. We tell you which before anyone sets off.
Outside Devon, we book a vetted independent technician near you where we have one. We are still building that network. Call and we'll tell you straight away whether we can get someone to you.
Why we repair and never delete
We don't delete AdBlue systems, fit emulators or reset countdowns without a repair. Here is why:
- It fails the MOT. Manufacturer-fitted emission control equipment that is missing, obviously modified or obviously defective is a major defect.
- The law is tightening. Using a vehicle altered so it no longer meets its emissions standard is already an offence on some vehicles. The Department for Transport has proposed extending that to all road vehicles from 2001 onwards, names AdBlue deletes, and expects new law in 2027.
- Lorry operators have been caught. DVSA roadside checks have found emissions cheat devices on lorries, and Traffic Commissioners can take away an operator's licence.
- A reset fixes nothing. The fault is still there, so the warning comes back.
Vans and small fleets
Vans are a big part of our AdBlue work. If you run several, call about them together: each gets its own triage and agreed price.
- Ask drivers to photograph the dash message and report it the day it appears.
- If several vehicles show AdBlue quality or efficiency faults around the same time, tell us. A shared bulk supply should be checked.
- Buy AdBlue made to ISO 22241 and keep containers sealed and clean.
AdBlue guides
What affects the cost
- Which part has failed, and whether it is sold on its own or only as an assembly
- The make, model and engine, including the set-up routine needed after the repair
- How much testing it takes to prove the fault
- Whether there is more than one fault
- Where the vehicle is, and whether the repair needs a workshop
- Whether a manufacturer support scheme covers part of the repair
We don't put AdBlue repair prices online because the same warning can mean very different repairs. Call with your reg and the warning message and we'll quote for your vehicle. How we quote
Who comes out
In Devon, our own technicians from the Totnes workshop. Outside Devon, we book a vetted independent technician near you where we have one.
Either way you deal with us: we quote, take payment and look after anything afterwards. Call and we'll tell you straight away whether we can get someone to you.
We repair. We don't delete.
We find the actual fault and fix it, so the vehicle stays road-legal and passes its MOT. We don't remove, disable or emulate AdBlue systems.
What customers say
Genuine Google feedback on our AdBlue, SCR and diagnostic work.
Google Review
Very impressed with the professional service offered. They diagnosed and sorted the adblue issues on my car, explained the process well and I believe the price was very reasonable. I would highly recommend them.
SD
sara dixon
AdBlue
Google Review
I took my VW Golf diesel to AutoClean after it went into limp mode with a flashing glow-plug light and suspected DPF blockage. Tom carried out proper diagnostics and confirmed the DPF itself was healthy. Instead of replacing parts unnecessarily, they identified a faulty DPF differential pressure sensor as the root cause. The issue was explained clearly, the costs were transparent, and the repair was completed promptly. Limp mode resolved immediately and no further work was pushed. I appreciated that they didn't default to a costly DPF removal when it wasn't needed. Good diagnostics, straightforward communication, and a proportionate fix. Would recommend if you're dealing with DPF or emissions-related issues.
MA
Martin Amis
DPF Diagnostics
Google Review
Very professional and incredibly helpful services from Tom at Auto-Cleanse, walked me through the findings on the diagnostic tool and thankfully didn't need a DPF clean! Excellent piece of mind and whilst I hope I don't need their services again (!) I will be recommending them to everyone!
CW
Callum Woodman
DPF Diagnostics
Frequently Asked Questions
In Devon, yes, where the fault allows; some repairs need our Totnes workshop. Outside Devon it depends on whether we have a vetted independent technician near you, so call and we'll tell you straight away.
Usually, until it reaches zero. Many vehicles then won't restart until the fault is fixed, and makes differ, so book the repair while it still runs.
Check you added the amount the dash or handbook asks for. If the warning stays after a short drive, the system has logged a fault that more fluid won't clear. Send us the codes or the dash message and we'll tell you what it points to.
It depends on which part has failed, the vehicle and where it is, so we don't publish prices. The price is agreed before any repair. Call for a quote for your vehicle.
Not as a fix for a road vehicle. A missing or obviously modified system is a major MOT defect, using a vehicle altered that way can be an offence depending on the vehicle, and the government has proposed covering all road vehicles from 2001 onwards. We only repair.
Yes. Call about several vehicles at once: each gets its own triage and agreed price, and you deal with one business for all of them.
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Ring with your reg and the warning message. We'll tell you what it's likely to be, who'd come out and what happens next.
Sources
- SAE International - J2012 diagnostic trouble code definitions
- UK legislation - Commission Regulation (EU) 2017/1151, Annex XVI: reagent warning and driver inducement
- ISO - ISO 22241-1, AUS 32 (AdBlue) quality requirements
- DVSA - MOT inspection manual for cars and passenger vehicles, section 8.2.2
- UK legislation - Road Vehicles (Construction and Use) Regulations 1986, regulation 61A
- Department for Transport - In-use emissions of road vehicles: regulating environmental impacts (consultation, 2026)
- DVSA - roadside checks for lorry emissions cheat devices
- Stellantis - urea (AdBlue) tank voluntary coverage
Last reviewed 13 October 2026.