P2458 and P2459: DPF regeneration duration and frequency
P2458 means regenerations are taking too long to complete; P2459 means they are happening too often. Both are the vehicle telling you that something is making soot faster than normal, and the filter is the symptom.
- Urgency
- Soon
- Reads the vehicle
- Your workshop
- Measures the filter
- Us
- Clean from
- ₹6,500
In plain words
P2458 is "Diesel Particulate Filter Regeneration Duration" and P2459 is "Diesel Particulate Filter Regeneration Frequency". The engine computer logs each regeneration it runs, how long it took and how often they occur. When a regeneration runs well past its expected length, or the interval between them collapses, these codes set.
Neither is a filter code in the usual sense. A filter that needs regenerating every few hundred kilometres instead of every few thousand is receiving far more soot than it was designed for, and the question is where the soot is coming from. A regeneration that will not finish is either being interrupted, or is trying to clear a filter that has ash underneath the soot and cannot reach its target pressure drop however long it burns.
Usual causes, most common first
- 01P2459: an injector with a poor spray pattern or internal leak, producing soot at several times the normal rate
- 02P2459: a sticking EGR valve recirculating too much exhaust gas
- 03P2459: a worn turbocharger giving insufficient boost and incomplete combustion
- 04P2458: regenerations repeatedly interrupted by short trips or switching off mid-cycle
- 05P2458: ash saturation, so the regeneration can burn all the soot and still not reach the pressure target
- 06Either: an exhaust temperature sensor reading low, so the regeneration never reaches its target temperature
In this order
Cheapest and least invasive first. Each step rules something out before you spend on the next.
Have your workshop read the regeneration counters, the soot and ash load, and look for injector, EGR, turbo and temperature sensor codes alongside. These codes rarely arrive alone.
For P2459, have the injectors tested for back-leakage and spray before anything is done to the filter. Cleaning first is money spent in the wrong order.
For P2458, if ash is high, the filter needs an off-vehicle clean; no regeneration will complete until the ash is out.
Once the upstream cause is fixed, have the filter measured. If it is loaded, clean it, so the repaired engine starts with a clear filter rather than one that is already half full.
What we find when the filter reaches us
Flow and back pressure are measured on arrival, before anything is quoted, and again after cleaning. Both readings go back with the filter.
- A filter from a P2459 vehicle is usually heavily sooted and cleans well, but comes back the same way within weeks unless the upstream cause is fixed; the report says so
- A filter from a P2458 vehicle at high mileage is usually ash-loaded, and the after reading shows why the regenerations were never completing
The symptom checker's view
The same pattern, scored from your answers. Each result links to the service that addresses it.
Asked about this one
It is a DPF code, but the fault is usually upstream. The filter is regenerating too often because it is receiving too much soot, and the sources of excess soot are injectors, EGR and the turbo. Cleaning the filter without finding which one resets the counter and nothing else.
Either it keeps being interrupted, by the journey ending or the engine being switched off, or it cannot reach its target because the filter is holding ash that burning cannot remove. The ash load reading from the ECU tells you which, and if ash is high the filter needs an off-vehicle clean.
Over time, yes. Each regeneration is a thermal cycle, and a filter run through several times the designed number of them ages faster and is more likely to crack. It also burns fuel every cycle. Fixing the cause early is cheaper than the filter it eventually costs.
Related problems
All problems and codesSend the code and a photograph
A picture of the scanner screen or the dashboard message, the vehicle and mileage, and how it is behaving. You will get a straight answer on whether the filter is the problem, and what it costs to find out.