Mobile AdBlue and NOx specialists
AdBlue tank heater fault?
The cold-morning warning, fixed.
The fault that only shows when it freezes. We measure the heater live and fix it in the software so winter stops mattering.
At home or work. Clear advice. A price agreed before work starts.
7 days a weekSame-day visits where available213 AdBlue faults fixed since May 2026
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
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1
Diagnose
Full diagnostics of the emissions system at your vehicle
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2
Attempt repair
Software repair and re-initialisation of the control modules
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3
Bypass
If necessary, a permanent bypass or deletion with a lifetime warranty
Start with your symptom
What’s happening with your vehicle?
Symptoms
How You Know It Is the AdBlue Tank Heater
The heater fault is the seasonal one. It surfaces in the first cold snap, often on vehicles that were fine all summer.
- AdBlue warning on cold mornings that clears as the day warms
- P20BA, P20B9 or P20BB heater codes stored
- A countdown that starts in winter after a run of cold starts
- No AdBlue consumption at all in freezing weather
- A dealer quote for a complete tank unit because the heater is sealed inside it
Fault Codes
The Codes You Will See
The heater has its own small family of codes. The resistance and current-draw test confirms it in a couple of minutes.
P20BA: reductant heater A control performance
The heater is commanded on but the control unit does not see the expected current draw. Open circuit in the element or its loom.
P20B9: reductant heater A control circuit low
A short to ground or a failed heater control relay or driver.
P20BB: reductant heater A control circuit high
Open circuit or a short to supply on the control side, often a connector under the vehicle.
Why It Fails
Cold, Corrosion and Sealed Tanks
The element sits in the tank and is thermally cycled every cold start. Elements fail open circuit with age; the loom and connectors underneath the vehicle corrode in road salt and fail intermittently, which is why the fault can come and go.
The expensive part is that on most vehicles the heater is sealed into the tank module with the pump and sensors. A failed element becomes a complete assembly, commonly £800 to £1,500 at a dealer, for a part that only matters a few weeks a year.
Dealer Repair or Our Fix
What a Dealer Charges, and What We Do Instead
A dealer replaces the sealed tank unit, commonly £800 to £1,500, for a part that only matters a few cold weeks a year. Where the fault is a corroded connector rather than the element, any garage can sort that cheaply.
We do not fit heaters or tank units. We measure the resistance and current draw live, show you the reading, and tell you which it is. If the element has gone, our permanent software fix from £250 means no heater, no winter countdown and a lifetime warranty. If it is the loom, you pay only for the visit and we tell you where to look.
- Diagnostic visit with control module resets £185: heater resistance and current draw measured live
- Full AdBlue fix from £250, diagnostic included, lifetime warranty
- No parts fitted, nothing on order, fixed on the day
Related
Read Next
See the full AdBlue fault code list, the AdBlue pump and injector pages, how we test the system at your vehicle, and the AdBlue warning light guide for what the dash message means.
How it works
A clear route to the right solution.
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01
Tell us the symptoms
Give us a few details about your vehicle and the issue.
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02
We diagnose at your location
Our mobile technician comes to you with the right equipment.
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03
You approve the next step
We explain the findings and agree the way forward.
Our pricing
Clear pricing. No surprises.
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 £250
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
AdBlue Tank Heater: Your Questions Answered
Because the heater is only commanded on when the fluid is near freezing. On a warm day it is never tested, so no code is set. The fault is there all year; the weather just reveals it.
A stored heater code can start a countdown on some vehicles, and the fluid cannot be dosed while it is frozen. If a countdown has appeared, do not wait.
Standalone heaters are rare. The sealed tank unit most vehicles use is commonly £800 to £1,500 at a dealer. We do not fit them. Our permanent software fix is from £250 with the diagnostic included.
The resistance and current-draw test at the connector tells us. Open circuit at the element is the heater; a good element with no current reaching it is the loom, relay or driver.
Let’s work out what your vehicle needs.
Speak to a specialist or request your free quote.