P2002
PowertrainDPF Efficiency Below Threshold (Bank 1)
Your diesel particulate filter (DPF) on bank 1 isn't filtering soot as effectively as the ECU expects. The downstream pressure or temperature readings indicate the DPF is no longer doing its job properly.
ⓘ Information only. This page provides general educational information about fault code P2002. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P2002 mean?
P2002 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: DPF Efficiency Below Threshold (Bank 1).
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • DPF warning light
- • Engine warning light
- • Limp mode in some cases, particularly if the DPF is also restricted
- • Increased fuel consumption (the engine attempts more frequent regenerations)
- • Smell of unburned diesel sometimes, especially after attempted regens
Possible causes
Causes commonly associated with P2002, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. DPF is full of soot and isn't completing regeneration properly. Massively common on cars used mostly for short urban journeys
- 2. Faulty differential pressure sensor reading inaccurately
- 3. Cracked DPF substrate, broken physically (often after attempting forced regens at very high mileage)
- 4. DPF temperature sensor faulty
- 5. Persistent regen interruption, drivers who switch the engine off mid-regen contribute to this
- 6. Coolant leak into the cat or DPF (head gasket failure or EGR cooler crack on engines that have one)
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. First, take the car for a 30-40 minute motorway run at sustained 70 mph. This is the 'Italian tune-up' for diesels, it gives the DPF a chance to regenerate properly. A surprising proportion of P2002s clear themselves after one good run
- 2. Read live data on differential pressure and DPF temperatures during the run. Healthy regen sees temps rise to around 600°C briefly
- 3. Check the differential pressure sensor and its hoses, blocked or split sample hoses give false readings
- 4. If repeated long runs and a forced regen don't clear the code, the DPF substrate is likely compromised
- 5. Address any other stored codes (boost, EGR, fuel pressure) before condemning the DPF, those upstream issues cause DPF blockage
Common questions about P2002
Mostly drive in town, can I get the DPF light to clear myself? +
Sometimes yes. Take the car onto a motorway or A-road and hold 70 mph in a higher gear (lower than top) for 30-40 minutes once a week. This gets exhaust temperatures high enough to burn off soot. Modern diesels need this kind of run regularly to keep the DPF healthy. If your driving never includes that, the DPF will keep blocking.
Can I just have the DPF removed? +
Removal makes the car illegal for road use and an automatic MOT failure. Workshops that offer 'DPF removal' are doing something that fails MOT. There are legitimate options: forced regen, ultrasonic DPF clean, or replacement. Don't pay anyone to physically gut the DPF.
Why does my fuel economy get worse with this code active? +
Two reasons. The ECU initiates regen cycles more frequently, each one injecting extra fuel post-combustion to raise exhaust temperatures. And a partially blocked DPF creates back-pressure that costs efficiency on every revolution. Both add up to noticeably worse mpg.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →