P242F: Diesel Particulate Filter Restriction - Ash Accumulation (Bank 1)
18 vehicles · 9 makes · $60-$12,000 repair
Most Reported On
P242F is an OBD-II diagnostic trouble code meaning “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. This code is most commonly reported on 2013-2019 Mercedes-Benz B-Class (B180 CDI, B200 CDI, B220 CDI), 2020-2025 Mercedes-Benz GLS (GLS 350d 4MATIC, GLS 400d 4MATIC), and 2019-2021 Porsche 718 Boxster (718 Boxster, 718 Boxster S, 718 Boxster GTS), plus 15 other vehicles, with repair costs ranging from $60 to $12,000.
Common Causes
Typical Repair Cost
Based on 18 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P242F, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (18)
OM651 Diesel DPF and EGR Clogging (B180 CDI / B200 CDI)
OM656 Diesel Emissions System Clogging (EGR/DPF/AdBlue SCR) and Limp Mode
DPF Regeneration Failure / Blockage (Short-Trip Use)
1.6 TDI (EA189) Dieselgate Recall and Post-Fix EGR/DPF Failures
2.0 TDI (EA189) EGR cooler cracking and DPF blockage
Diesel particulate filter (DPF) clogging and regeneration failure
1.6 TDI DPF clogging and oil dilution on short-journey use
FAQ
What does P242F mean?
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.
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?
Repair costs for P242F range from $60 to $12,000, depending on the vehicle and root cause.
Which vehicles are affected by P242F?
Au7o has documented P242F across 18 vehicle models from 9 manufacturers: Ford, Mazda, Mercedes-Benz, Opel, Porsche, SEAT, Skoda, Volkswagen, Volvo.
Sources (12)
- articleCommon Problems of Mercedes-Benz B-Class W246 B 200 CDI: A Comprehensive Guide - EuroAutoPro
- articleOM651 Engine: Full Guide & Known Issues - Mercedes Assistance
- ForumB200 CDI EGR Blanking / DPF discussion - MBClub UK
- ForumMercedes GLS X167 400 Diesel / Probleme beim Beschleunigen - MOTOR-TALK
- articleMercedes OM656 Diesel: Haeufige Probleme, Ursachen & Tipps - MBPassion.de
- articleMercedes-Benz OM656 engine - Wikipedia
- ForumPetrol Particulate Filter Failure - Porsche Club GB Forum
- ForumCayman 718 2.0 2019 GPF issues - Porsche 718 Forum
- ForumFord Fiesta TCDI 2016 DPF Regeneration — Ford Owners Club
- articleFord Diesel Particulate Filter DPF FAQ — Fiesta / Focus / Mondeo
- ForumDPF regeneration cycle - Mazda CX-70 Forum
- articleDieselgate: how the emissions fix affects your DPF in VW/Audi/Skoda/SEAT (Hypermiler)
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.