Updated August 2025 — by Gianni Tritella. Error code P2459 : DPF regenerations too frequent. Analysis of symptoms, causes, and solutions.
📋 Article Index
Updated 08/20/2025 • Based on workshop diagnoses, TSB and driver feedback
✅ Introduction
The P2459 error code indicates that the diesel particulate filter (DPF) is regenerating at an abnormally frequent rate. Excessive regeneration not only reduces efficiency but can also lead to increased fuel consumption, oil dilution, and possible engine damage . Let's take a detailed look at the symptoms, causes, and solutions.
⚠ Symptoms of P2459
- Frequent illumination of the DPF warning light
- Increased oil level due to unburned diesel fuel
- Radiator fan often active even with engine off
- Possible drop in performance and higher than normal consumption
🔍 Main causes
- Short journeys → the DPF never reaches the correct temperature
- Exhaust gas temperature sensors out of specification
- Inefficient thermostat → engine does not reach the ideal thermal range
- Low-quality fuel that increases particulate matter formation
🔧 Solutions and interventions
- Replacing worn EGT (Exhaust Gas Temperature) sensors
- Checking and resetting the engine thermostat
- Take a long extra-urban journey (20–30 min) to complete the regeneration
- In selected cases, use of professional DPF additives recommended by the workshop
AREXONS 3705 – FAP/DPF CLEANING KIT
Specific product for cleaning the particulate filter. Helps prevent clogging, promotes regeneration, and keeps the DPF efficient over time.
💡 Practical advice
To prevent P2459 from returning, regularly drive 15–25 km (9–15 mi) on an extra-urban route at a steady engine speed . This allows regeneration to complete and keeps the DPF filter efficient.
❓ FAQ - Frequently Asked Questions
How much does it cost to replace DPF sensors?
An EGT sensor ranges between €70 and €150 plus labor.
Does the P2459 code disappear after a forced regeneration?
Yes, but if the cause (sensors or thermostat) is not resolved, the error will return.
Are DPF additives always recommended?
No, they should only be used when indicated by the workshop or product manufacturer.
📌 Conclusions
P2459 is a clear sign that the DPF is regenerating too often . Adjusting the sensors, thermostat, and driving style are essential to reduce the problem. Proper maintenance and regular out-of-town driving will prolong the filter's life and avoid costly replacements.
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