OBD-II Code
P2459
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$150–$5,000
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$150 (sensor or pressure tap line) to $5,000 (full DPF replacement on a 6.4 Powerstroke).
P2459 means the ECU has determined that the diesel particulate filter is requesting active regenerations too frequently — the time or distance between commanded regen events has fallen below the calibrated threshold, indicating either that the DPF is loading abnormally fast or that the regen process itself isn't completing successfully each cycle.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP2459 means the ECU has determined that the diesel particulate filter is requesting active regenerations too frequently — the time or distance betwee…
P2459 means the ECU has determined that the diesel particulate filter is requesting active regenerations too frequently — the time or distance between commanded regen events has fallen below the calibrated threshold, indicating either that the DPF is loading abnormally fast or that the regen process itself isn't completing successfully each cycle. A healthy modern DPF regenerates every 300-700 miles depending on duty cycle; P2459 typically sets when the gap drops under 100 miles or the regen-completion count fails.
The cheapest-first ladder
- scan-tool the DPF soot-load percentage, time-since-last-regen, distance-since-last-regen, and the count of completed vs aborted regens.
- A regen that consistently aborts before completing means exhaust temperatures aren't reaching the 1,100-1,300 F target — check the EGT sensors first (DPF inlet and outlet thermocouples should read within 20 F of each other at cold start and ambient temperature).
- A clogged or contaminated 9th injector / fuel doser on Duramax and Cummins applications is the leading cause of failed regens; flow-test or replace the 9th injector.
- Check for EGR-cooler internal leaks (coolant entering the exhaust stream destroys regen temperature and corrodes the DPF) — sweet smell from the exhaust during regen is the field tell.
- Verify that boost and air mass flow are in spec during regen; a leaking intercooler or charge-air-cooler pipe makes regen impossible.
- The expensive-misdiagnosis caveat: don't replace the DPF on a P2459 — the DPF itself is almost never the cause of frequent-regen codes, the cause is upstream in the regen-fueling system or the EGR/turbo air path; a 6.7 Cummins or Powerstroke DPF replacement is $2,500-$5,000 and won't fix a clogged 9th injector.
Vehicle-specific patterns2011-2016 Duramax LML (Silverado HD, Sierra HD) is the leading P2459 platform — the 9th injector (fuel doser) clogs from biofuel deposits and active…
- 2011-2016Duramax LML (Silverado HD, Sierra HD) is the leading P2459 platform — the 9th injector (fuel doser) clogs from biofuel deposits and active regens never reach completion temperature; GM has a TSB covering 9th injector replacement procedures. 2007.5-2010 LMM Duramax throws P2459 from a known issue where the EGR cooler develops internal coolant leaks that destroy regen efficiency; a coolant-loss complaint plus P2459 is the diagnostic combo.
- 2011-2018RAM Cummins 6.7 throws P2459 when extended idle time loads the DPF faster than the highway-regen schedule can clear; a forced service regen clears it but the underlying duty-cycle mismatch repeats.
- 2008-2010Ford 6.4 Powerstroke throws P2459 from oil dilution that reduces in-cylinder post-injection effectiveness — check engine oil for fuel content above 5%.
- 2011-2019Ford 6.7 Powerstroke throws P2459 from failing EGT sensors or a contaminated DPF inlet pressure tap line.
Estimated repair$150 (sensor or pressure tap line) to $5,000 (full DPF replacement on a 6.4 Powerstroke).
Look up another code
More free tools