P2459Generic code

P2459 Code: Diesel Particulate Filter Regeneration Frequency

The P2459 code means the diesel particulate filter has to regenerate too often, because the engine makes more soot than normal or the sensor misjudges the load. Drive with caution and head to a shop, because a filter that cannot keep up ends up in limp mode.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$50 to $2,500
Difficulty
Medium
System
Emissions Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

On this page

What the P2459 code means

The diesel particulate filter (DPF) traps soot from a diesel engine. When it fills up, the computer burns the soot off in a regeneration: it raises the exhaust temperature above 550 °C (1,020 °F) for a few minutes, usually while you drive at a steady speed. A differential pressure sensor measures the back pressure across the filter to estimate how much soot it holds.

The computer counts the distance between regenerations. If it is repeatedly very short, it stores the P2459 code.

Before you replace the filter, rule out the things that stop it from regenerating: sensors, an EGR valve leaking soot, leaking injectors, a thermostat stuck open, or oil that is not rated for diesel particulate filters.

P2459 code symptoms

  • Check engine light or DPF warning light on.
  • Loss of power or limp mode.
  • Cooling fan running after you shut off the engine during a regeneration.
  • Higher fuel use.

Likely causes of the P2459 code

  1. Excess soot from the engine because of injectors, the EGR, intake leaks or the turbo.
  2. Differential pressure sensor or its hoses giving a false load reading.
  3. City driving with short trips. Confirm it with the tests in the diagnosis section.
  4. Filter loaded with ash at the end of its life.

How to diagnose the P2459 code step by step

  1. Read the estimated soot load and the differential pressure in the live data.
  2. Check the pressure sensor hoses, which crack or clog.
  3. Check the exhaust temperature and the EGT sensors.
  4. Check the engine codes. Injectors, the EGR and the turbo can produce excess soot.
  5. Try a forced regeneration with the scan tool, following the manufacturer conditions.

How to fix the P2459 code

  • Do a regeneration on the road: 20 to 30 minutes at a steady highway speed.
  • Run a forced regeneration with the scan tool if the soot load allows it.
  • Repair the cause of the excess soot.
  • Clean or replace the filter if it is loaded with ash.
  • Use oil that meets the DPF specification (low ash).

Technical reference data

  • Regeneration temperature: 550 to 650 °C (1,020 to 1,200 °F).
  • Differential pressure with a clean filter at idle: normally a few millibars (well under 1 psi).
  • Approximate values only: check the manufacturer data for your vehicle.

Brand-specific notes

Check for engine problems that make soot before you blame the filter. The P2459 code often means the engine is making too much soot, not that the filter is bad.

P2459 on Diesel Vehicles From Many Makes

Common on diesels from Volkswagen, Audi, Seat, Peugeot, Citroen, Renault, Ford, Mercedes-Benz, BMW, Toyota Hilux, Nissan Navara and Chevrolet. Short city trips are the filter worst enemy.

Frequently asked questions about P2459

Can I drive with a P2459 code?
With caution and toward a shop. The P2459 code means the filter is regenerating too often, and a filter that cannot keep up ends up in limp mode.
Can the filter be cleaned?
Yes. Many shops clean filters with specific equipment, and it is cheaper than replacing one.
Why does it fill up so fast?
Short trips, faulty injectors or EGR, or oil that is not rated for the filter.
What does the P2459 code mean?
It means the DPF is regenerating more often than the computer expects, either because the engine makes too much soot or because the load is being misread.
How much does it cost to fix P2459?
Roughly $50 to $2,500. A sensor hose or a forced regeneration is at the low end, and a new filter costs the most.

Related codes

Questions about the P2459 code

There are no questions about this code yet. Tell us about your case: vehicle, symptoms and what you have already checked.