AdBlue warning on and you need a quick answer?
Here are the most common AdBlue and SCR fault codes, what they usually mean, and what to do next before you hit a no-start countdown.
Modern Peugeot, Citroën and Ford vans often suffer from recurring AdBlue fault codes. While these codes look confusing on a scan tool, they all point to common problems inside the SCR system. Here’s a breakdown of the top five we see in 2025, what they mean, and how they’re fixed with our mobile service in Stoke and Staffordshire.
1. P20EE – SCR NOx Catalyst Efficiency Below Threshold
This fault is one of the most frequent across Peugeot Boxer and Citroën Relay vans. It usually means the SCR system isn’t reducing emissions properly, often due to a failing NOx sensor or poor AdBlue dosing. We offer quick mobile resets and can provide permanent fixes for repeat cases. Read our Peugeot P20EE guide here.
2. P20E8 – Reductant Pressure Too Low
Common in Ford Transit and Peugeot vans, this code indicates that the AdBlue pump isn’t creating enough pressure. Causes include a weak pump motor, frozen fluid in winter, or leaks in the system. Learn more about pump vs heater faults and how to spot them before they stop your van completely.
3. P204F – Reductant System Efficiency
This broad code often flags up when the system struggles to inject AdBlue correctly. It can be triggered by a blocked injector, failing pump, or corrupted software data. Many Mercedes Sprinters throw the same code, showing how widespread it is across different makes.
4. P20E9 – Reductant Pressure Too High
Seen regularly on Vauxhall Movano and Citroën vans, this code means the system is over-pressurising the AdBlue tank. It can cause leaks or system shutdowns if not addressed. We explain this in detail in our Movano P20E9 guide.
5. U029D – Lost Communication with NOx Sensor
This fault means the ECU has lost contact with the downstream NOx sensor. It’s particularly common on Peugeot and Citroën vans and can trigger limp mode quickly. If repeated NOx faults appear, many owners choose a NOx sensor delete as a permanent solution.
What Happens If These Codes Are Ignored?
Ignoring AdBlue fault codes leads to bigger problems:
- Reduced performance in limp mode.
- Dashboard countdowns such as “No start in 500 miles.” (see more).
- Costly breakdowns requiring recovery if the van won’t restart.
How Mobile Fixes Work
Our mobile service means we come to you across Stoke, Stafford, Crewe and Burton upon Trent. We can reset codes, repair faulty parts, or carry out permanent deletes for off-road/export vehicles. Most jobs take less than an hour, so downtime is minimal.
Stay Ahead of 2025 Rules
With Euro 7 regulations tightening requirements on vans, ignoring codes isn’t an option if you plan to stay road-legal. We’ll explain which fixes keep you compliant and which are intended for off-road or export vehicles only.
Book a Fix for Your Van
If your Peugeot, Citroën, or Ford is showing one of these AdBlue fault codes, call 07503 134 362 or email info@adbluespecialist.co.uk. Same-day mobile appointments are available across Stoke-on-Trent and Staffordshire most weeks.
For most AdBlue fault codes, you have two options:
1. Professional AdBlue repair – We diagnose and fix the
faulty component (pump, sensor, heater, etc.)
2. Permanent AdBlue removal – We disable the entire
system, preventing future faults. Most customers choose this for peace of mind.
Found Your Fault Code?
Don’t know what to do next? Our AdBlue fault repair service covers all codes and provides same-day fixes.
Expert technicians. Mobile service. Call now for a quote.
