When your AdBlue warning light comes on, it’s not just a small nuisance — it’s your van’s way of saying something inside the SCR system is going wrong.
Leave it too long and the dash countdown could drop to “0 miles until no start.” Here are the key symptoms to look out for and how our
mobile AdBlue delete and repair service can keep you moving.
1. Persistent AdBlue Warning Light
The most common early clue is a permanent AdBlue light that won’t reset after topping up.
This often means the system isn’t reading fluid level correctly due to a faulty tank sensor or dosing module.
On many Peugeot Boxer and Ford Transit models, we see this triggered by crystallised build-up on the level sensor.
A quick scan during a mobile diagnostic visit confirms the exact fault before it locks you out completely.
2. Countdown to “No Start”
Once your display shows a countdown in miles to no start, the ECU has detected repeated SCR faults.
You might still drive for a few hundred miles, but once it reaches zero the engine will refuse to start.
Our team clears these countdowns safely using genuine test fluid and software resets — see our
AdBlue Fault Code Reset guide for more detail.
3. Low AdBlue Pressure Fault Codes (P20E8 / P204F)
Codes such as P20E8 or P204F indicate a weak pump or blocked filter.
You’ll notice the AdBlue level drops slower than normal, or you might smell ammonia near the rear of the van.
Ignoring this can damage the injector and SCR catalyst. We replace failed pumps or, when repair costs outweigh the van’s value, perform a
software-only AdBlue delete that removes the fault without cutting or drilling.
4. Crystallised AdBlue Around the Tank or Lines
Dried white crystals mean AdBlue has leaked and evaporated.
This is common on Mercedes Sprinter vans where the heater element corrodes and drips fluid onto wiring.
Crystals block sensors and injectors, leading to “SCR efficiency below threshold” warnings.
A proper fix involves cleaning the lines and resetting system pressure — something we do on-site across Leicestershire.
5. Sudden Increase in DEF Consumption
If your AdBlue usage doubles, it’s a red flag for a dosing module fault or bad NOx sensor.
We’ve seen Transits using 5 litres per week due to a stuck injector.
Not only does this waste fluid, it can clog the SCR brick and raise exhaust temperatures.
Our SCR system repair service includes live-data checks to confirm correct dosing.
6. Poor Starting or Power Loss
The SCR system communicates with your engine ECU; when faults appear, the ECU limits torque to protect emissions.
You’ll feel reduced acceleration or limp mode when climbing hills.
A quick diagnostic identifies whether the issue stems from AdBlue pressure, EGR feedback, or DPF regen interruptions.
In some cases, a calibrated AdBlue delete restores full performance safely for off-road or export vehicles.
7. “Service AdBlue System” Message Appears Randomly
Many drivers see this even after dealer software updates.
It’s often caused by mismatched firmware between the engine and SCR modules.
We use Autotuner & CMD Flash tools to update both systems together, ensuring the message stays off for good.
This software-first approach avoids unnecessary parts swapping and saves hundreds compared with main-dealer rates.
Don’t Wait Until Your Van Won’t Start
Whether you drive a Transit, Ducato, or Sprinter, ignoring these AdBlue symptoms can leave you stranded.
iFixAdBlue offers same-day mobile repairs across Leicestershire and nearby counties.
We diagnose, reset, or safely remove AdBlue systems without cutting or drilling.
Book Your Mobile Visit or call 07349 821 999 to get the warning gone today.
Frequently Asked Questions
Can I drive with the AdBlue warning light on?
You can usually drive for 500–1000 miles depending on model, but once the countdown hits zero the vehicle will not restart.
It’s best to call our mobile unit before that happens.
Does an AdBlue delete remove the warning light permanently?
Yes — a professional software delete disables the SCR monitoring while leaving the rest of the ECU intact.
We only use trusted tools and always explain the legal implications before proceeding.
Can a faulty NOx sensor cause AdBlue warnings?
Absolutely. Fault codes P20EE or P229F are linked to NOx sensor failure, which prevents correct AdBlue dosing.
See our NOx Sensor Delete vs Replacement guide for your options.
