Mapping of Code P1445: Limit of Particle Additives in Citroën DPF Filters

Unveiling the P1445: The Critical Point of the Citroën Particulate Filter

If you work on Citroën diesel vehicles, especially the BlueHDi engines or the older 2.0 HDi engines, you’ve probably encountered the dreaded \”Anti-pollution System Fault\” message. This happens when you plug in the scanner and the code appears. P1445Many people get confused. Unlike other DTCs that point to failing differential pressure sensors, P1445 is a mathematical and physical warning: it indicates that the total amount of additive (Eolys) injected into the fuel tank since the vehicle’s manufacture has reached the maximum limit supported by the ceramic core of the DPF (Diesel Particulate Filter).

We’re not just dealing with an empty additive tank, but with saturation by non-combustible residues that the additive leaves behind. This article explores the nuances of this diagnosis and how to proceed to not just turn off the light, but to resolve the root cause.

Understanding the Origin of the Problem: The Role of the Eolys Additive

The PSA system uses an active additive strategy. Eolys fluid (based on cerium dioxide) is mixed with diesel at each refueling to reduce the combustion temperature of soot inside the DPF. However, while the soot burns and turns into CO2, the cerium does not evaporate. It physically accumulates in the filter honeycombs in the form of ash.

The P1445 code is generated by the BSI or the engine ECU when an internal counter estimates that the volume of this ash has reached a level that compromises exhaust backpressure. Common symptoms include:

• Emergency mode (Limp Mode) with torque limitation;
• Deactivation of the active regeneration system;
• Radiator fan remaining on for extended periods after the car is turned off;
• Persistent error message on the instrument panel.

Step-by-Step Diagnosis: Checking Beyond the Scanner

Many repair technicians make the mistake of simply attempting to \”reset\” the fuel meter without checking the physical condition of the part. This results in a guaranteed return in less than 500 km. Follow this technical guide:

1. Backpressure Analysis

Using the scanner in \”Parameter Reading\” mode, monitor the differential pressure of the DPF with the engine idling at 3,000 RPM. At idle, the values ​​should be between 0 and 5 mbar. Above 20 mbar at rest indicates high physical saturation.

2. Checking the Additive Level

Check if the additive reservoir (or bag) still contains fluid. P1445 is often accompanied by P1446 (insufficient level). If the bag is dry, the ECU assumes that the filter’s life cycle has also ended.

3. Electrical Integrity

Although P1445 is logical, power supply failures in the additive module can corrupt the data. Check the protection fuse (usually located on the BSM, varying between 5A and 10A depending on the model as C4 Lounge (or Jumpy). Clean the additive pump connectors located near the fuel tank to remove any oxidation.

Solution and Technical Intervention

To resolve error P1445, there are three main approaches, depending on the vehicle’s condition:

The Reset Procedure

After replacing or deep cleaning the component, it is mandatory to use a diagnostic interface (Diagbox or similar professional tool) to inform the system that a new filter has been installed. The path is usually: Repair > Maintenance Pack > Particulate Filter > Filter Replacement. Without this step, the ECU will continue to operate under the flow restriction logic of the old filter.

Parts, References and Costs

Working with the FAP line requires precision in fluid selection. Never use regular diesel in place of Eolys additive; this will destroy the injectors and the filter.

• Additive: There are variations such as Eolys PowerFlex or Extend. Check the color of the quick-connect fittings on the tank (blue, green, or white) to determine the correct fluid.
• FAP filter: The OEM code varies, but for 1.6 BlueHDi engines, references close to 16 091 638 80 are commonly used.
• Estimated Costs: In Brazil, a professional DPF cleaning ranges from R$ 800.00 to R$ 1,500.00. A new original filter can exceed R$ 6,000.00, while refilling the additive costs between R$ 700.00 and R$ 1,200.00 depending on the volume.

Golden Tips from the Expert

In my workshop experience, 40% of P1445 cases are caused by drivers who only make short urban trips, preventing the completion of regenerations and forcing excessive use of coolant. Another critical point: always check the differential pressure sensor hoses. If one of them is cracked, the ECU will make incorrect saturation calculations, triggering the P1445 much earlier than expected.

If the vehicle is exhibiting constant white smoke and error code P1445, suspect a leaking fuel injector. Excess diesel fuel accelerates DPF contamination, and the system attempts to compensate with more additive until it exceeds the software limit.

Conclusion

The P1445 code isn’t rocket science, but it requires an analysis that goes beyond simply clearing error codes on the dashboard. It’s a warning that the exhaust system has reached its operational maturity. When diagnosing, always focus on the differential pressure and the calculated lifespan of the pressure gauges. Treating only the symptom and ignoring the physical saturation of the filter is a sure way to get your car towed back in a few days.

Disclaimer

This article is for informational and reference purposes only. The content published here was compiled from publicly available technical information, workshop experience, and general market references, and does not, under any circumstances, replace the diagnosis and intervention of a qualified mechanic or authorized dealership. The website is not responsible for any damages, losses, or consequences arising from the practical application of the guidelines described here. Always confirm part codes, torques, and procedures in the manufacturer’s official manual before any repair.