P242F on Ford: How to Diagnose & Fix
Diesel Particulate Filter Restriction - Ash Accumulation (Bank 1)
1 Ford model · 1 documented issue · $400-$2,500 repair
P242F on Ford by model: symptoms, diagnosis and fix
Diesel Fiestas frequently suffer diesel particulate filter (DPF) blockage and incomplete/failed regeneration, especially on cars used mainly for short, low-speed journeys that never reach regeneration temperature. Soot accumulates, the DPF warning light appears, and the car may enter limp mode or dump excess fuel into the oil during failed active regens (raising oil level and diluting it). Underlying triggers are often other faults — a leaking/faulty injector, stuck EGR, blocked intake, or failed DPF differential-pressure/EGT sensor — so the blocked DPF is frequently a symptom rather than the root cause.
Common Symptoms
- DPF / exhaust warning light
- Limp mode / reduced power
- Frequent regeneration attempts
- Rising engine oil level (fuel dilution)
- Excess smoke or smell
- Poor fuel economy after failed regen
How to Fix
When the DPF light shows, drive at a steady 40+ mph for ~20 minutes to allow passive/active regeneration before it fully blocks. If blocked, run a forced regeneration and diagnose the root cause: test the DPF pressure and EGT sensors, check EGR operation, and inspect for a leaking injector causing oil dilution. Clean or replace the DPF if soot loading is beyond limits, and change oil if fuel-diluted.
Sources for this issue (1)
P242F code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P242F mean on a Ford?
P242F stands for "Diesel Particulate Filter Restriction - Ash Accumulation (Bank 1)." P242F is a generic diesel emissions code indicating the engine control module has detected excessive restriction in the Diesel Particulate Filter (DPF) caused by ash accumulation rather than recoverable soot. Unlike soot, ash cannot be burned off through normal or forced regeneration, so this typically signals the DPF is reaching the end of its service life and needs cleaning or replacement. The condition reduces exhaust flow and can trigger reduced-power (limp) mode if left unaddressed. On Ford it is documented across 1 model: Fiesta.
What are the most common causes of P242F?
The most common causes of P242F are: DPF at end of service life with accumulated non-combustible ash from engine oil additives, Excessive oil consumption (worn rings/valve seals) loading the filter with ash, Use of non-low-ash (non-CJ-4/low-SAPS) engine oil, Repeated incomplete or failed regeneration cycles over time, Faulty DPF differential pressure sensor giving high restriction readings, Clogged or saturated DPF substrate requiring professional cleaning or replacement. The specific cause varies by vehicle.
How much does it cost to fix P242F on a Ford?
Published repair estimates on Ford range from $400 to $2,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.