U029D and U029E Fault Codes: Lost Communication With a NOx Sensor
U029D means the engine control unit has lost contact with NOx sensor A (U029E is sensor B). Why it isn't always the sensor, what both codes…
Read articleMobile AdBlue and NOx specialists
Mobile diagnostics and the permanent software fix, done at your vehicle. We come to you.
At home or work. Clear advice. A price agreed before work starts.
7 days a weekSame-day visits where available249 AdBlue faults fixed since May 20264.9 from 12 Google reviews (opens Google)
Let's get you moving
Tell us about your vehicle.
Enquiry received, thank you.
We will text your quote shortly. If it is urgent, call 0207 046 1823.
Our process
Diagnose
Full diagnostics of the emissions system at your vehicle
Attempt repair
Software repair and re-initialisation of the control modules
Bypass
If necessary, a permanent bypass or deletion with a lifetime warranty
Start with your symptom
Our services

Full system diagnostics, fault-code reading and live data analysis at your vehicle.
Explore serviceDiagnose and resolve NOx sensor, SCR and emissions system faults in the software.
Explore serviceP20EE, P20E8, P204F and the rest: what each means and what actually fixes it.
Explore servicePermanent software fix with a lifetime warranty. Eligibility checked first.
Explore servicePopular vehicles
Ford · Mercedes-Benz · Volkswagen · Peugeot · Citroën · Vauxhall · All makes

P20EE and countdown faults on 2.0 EcoBlue, fixed on the drive.
View vehicle guide
NOx sensors and sealed tank units, fixed without the parts bill.
View vehicle guide
Emissions fault, starting prevented: cleared at your vehicle.
View vehicle guideFault Code Reference
We see these codes most often. Full diagnostics are always recommended — codes give us a starting point, not the full picture.
Don’t see your code? See every AdBlue fault code explained, or send us your fault details
Mark T.
Crawley • Mercedes Sprinter
“Sprinter went into countdown mode with 120 miles showing. These guys came to my yard in Crawley the next morning, diagnosed a faulty NOx sensor and had it sorted by lunchtime. Proper professional setup too.”
Lisa P.
Redhill • Audi Q5
“Dealer quoted over two grand to replace the AdBlue tank. Technician came to my house, found it was actually a NOx sensor causing the cascade of warnings. Fixed it for a fraction of the dealer price. Clear, honest, no hard sell.”
Steve M.
Horsham • Ford Transit Custom
“Transit went into limp mode just outside Horsham with AdBlue warning flashing. Called at 7am, had someone with me by 11 the same day. Diagnosed an SCR pressure fault, explained it in plain English, got me running again.”
How it works
Tell us the symptoms
Give us a few details about your vehicle and the issue.
We diagnose at your location
Our mobile technician comes to you with the right equipment.
You approve the next step
We explain the findings and agree the way forward.
Our pricing
Diagnostic visit
£185
Fault-code and live-data checks, control module resets and written findings. Included if you go ahead with the full fix on the day.
AdBlue software service
From £249
Diagnostics included. Lifetime warranty on the work. Vehicle and use eligibility checked first.
ECU unlocking, where required, is quoted separately before work starts. What the lifetime warranty covers.
Get a fixed quoteFAQ
Yes — AdBlue countdown warnings are one of the most common reasons people call us. When your dashboard shows a countdown in miles, your vehicle may refuse to restart once it reaches zero. We come to your location, diagnose the underlying fault and provide a solution. The sooner you contact us, the more options you typically have. Where the answer is our software fix, it is permanent unless you ask us to reverse it.
Yes — we are a fully mobile service. Our technicians come to your home, workplace or roadside location across all of London, Surrey, Sussex, Kent and the surrounding areas with professional diagnostic equipment. You don’t need to arrange recovery or take your vehicle anywhere.
Same-day visits are usually possible, and we operate 7 days a week across our coverage area. When you contact us, we’ll give you an honest estimate of when we can reach you — usually much faster than a main dealer or traditional garage.
We provide mobile AdBlue diagnostics across all of London, Surrey, Sussex, Kent and the surrounding areas including Crawley, Gatwick, Horsham, Redhill, East Grinstead, Brighton, Worthing, Guildford, Woking, Sevenoaks, Maidstone, Croydon and Bromley. For the capital, our AdBlue delete in London page lists the boroughs and postcodes we cover. If you’re just outside these areas, give us a call — we may still be able to help.
No, you don’t need a fault code — though if you have one it’s helpful. Just tell us what you’re experiencing: what warning lights are showing, any dashboard messages, and what the vehicle is doing differently. We’ll run our own full diagnostic when we arrive.
Latest guides
U029D means the engine control unit has lost contact with NOx sensor A (U029E is sensor B). Why it isn't always the sensor, what both codes…
Read article
A NOx sensor fault in Guildford usually means a countdown has started. Here's what the codes mean, why sensors fail and how a mobile software fix…
Read article
P207F means the engine control unit doesn't trust the AdBlue quality. Why it isn't always bad fluid, the codes it comes with, what to check yourself…
Read article
An AdBlue no start countdown in Croydon? Learn what triggers it, why refills don't clear it, and how a mobile ECU fix sorts it at your…
Read articleSeeing “check anti-pollution system” on the dash? Read what the message means and what causes it, or browse all our guides.
Speak to a specialist or request your free quote.