P242F on Mazda
Diesel Particulate Filter Restriction - Ash Accumulation (Bank 1)
P242F on Mazda vehicles indicates diesel particulate filter restriction - ash accumulation (bank 1). Au7o has documented this code across 1 Mazda model — most commonly on CX-60. 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.
Common Causes of P242F
- •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
P242F on Mazda by Model
Mazda CX-60(1 issue)
- Diesel DPF Frequent Regeneration and Poor Economy on Short Trips2022-2025
3.3L diesel CX-60 owners report the diesel particulate filter (DPF) entering active regeneration very often, particularly on short/urban journeys where the exhaust never reaches full temperature. During a regen the engine injects extra fuel to burn off soot, driving instantaneous consumption up to ~15-17 L/100km and dropping average economy to the mid-20s mpg. Owners who do mostly short trips risk incomplete regens, a partially clogged DPF, and eventually a limp-mode/emissions warning. Mazda advises a periodic 30-45 minute higher-speed drive to complete a regen.
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View P242F across all makes →Frequently Asked Questions
What does P242F mean on Mazda?▼
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 Mazda specifically, this code is documented across 1 model.
What causes P242F on Mazda vehicles?▼
Common causes on Mazda: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P242F on a Mazda?▼
Repair costs vary widely depending on the root cause and specific Mazda model.
Which Mazda models have P242F documented?▼
Au7o has documented P242F on 1 Mazda model: CX-60.