Soot buildup from too much low-speed or short-trip driving. Diesel particulate filter failure or damage. Air or exhaust leak ahead of the DPF throwing off the sensor readings. Dirty or out-of-calibration mass airflow (MAF) sensor. Faulty DPF pressure sensors, wiring or connectors. Engine computer faults or components that prevent regeneration. High-sulfur fuel clogging the filter. Dirty air filter, or aftermarket intake/exhaust modifications.

Complete a DPF regeneration (driven or shop-forced with a scan tool). Repair air or exhaust leaks ahead of the DPF. Clean or replace the MAF sensor. Repair DPF pressure sensor wiring or replace a faulty sensor. Replace a damaged or failed DPF. Change the engine oil if it's been diluted by fuel.

P2002🌫 Emissions / diesel aftertreatmentDrive with caution, fix soon

P2002: Diesel Particulate Filter Efficiency Below Threshold (Bank 1) (Meaning, Causes, Fixes)

Q: What does P2002 mean?

P2002 means the engine computer thinks the diesel particulate filter (DPF) on Bank 1 isn't working within its limits, usually judged from pressure sensors before and after the filter. Most often the filter is clogged with soot that hasn't burned off, commonly from lots of short, slow trips. It's a generic code seen on 2007-and-later diesels. A diesel particulate filter sits in the exhaust and traps soot. OBD-Codes.com explains that it creates a slight back pressure, and the engine computer uses pressure-feedback sensors on the DPF to monitor it. If it sees the pressure outside its limits (OBD-Codes.com says for two running cycles), it sets P2002. The filter normally cleans itself by regeneration, which needs high exhaust heat (OBD-Codes.com cites roughly 500 to 600 °C), so vehicles driven mostly at low speed have trouble clearing it. P2002 is the Bank 1 version; P2003 is the same fault on Bank 2. It is an SAE generic code, but repair steps vary by make, and it is listed sixth in the 2026 carfaultcodes.co.uk review of UK fault code data. How sources explain it differs: OBD-Codes.com frames it around soot buildup and the DPF pressure sensors, while RepairPal's explanation ties it to diesel exhaust fluid (DEF) injection and the SCR catalyst. Follow your manufacturer's service information for your vehicle's exact strategy.

Q: Can I keep driving with P2002?

Drive with caution, fix soon. Sources disagree on how urgent this is. OBD-Codes.com describes P2002 as often a 'soft' code that can clear itself once the DPF regenerates (burns off its soot), while RepairPal rates P2002 as 'Urgent'. Both agree it shouldn't be ignored: OBD-Codes.com notes that if the DPF isn't cleared, the engine computer can put the vehicle into limp-home mode, and repeated regeneration attempts can dilute engine oil with fuel. Get it checked soon, and sooner if you notice limp mode, sluggish acceleration or a rising oil level.

Reviewed 2026-10-21 · Based on 3 cited source(s)

What P2002 means

A diesel particulate filter sits in the exhaust and traps soot. OBD-Codes.com explains that it creates a slight back pressure, and the engine computer uses pressure-feedback sensors on the DPF to monitor it. If it sees the pressure outside its limits (OBD-Codes.com says for two running cycles), it sets P2002. The filter normally cleans itself by regeneration, which needs high exhaust heat (OBD-Codes.com cites roughly 500 to 600 °C), so vehicles driven mostly at low speed have trouble clearing it. P2002 is the Bank 1 version; P2003 is the same fault on Bank 2. It is an SAE generic code, but repair steps vary by make, and it is listed sixth in the 2026 carfaultcodes.co.uk review of UK fault code data. How sources explain it differs: OBD-Codes.com frames it around soot buildup and the DPF pressure sensors, while RepairPal's explanation ties it to diesel exhaust fluid (DEF) injection and the SCR catalyst. Follow your manufacturer's service information for your vehicle's exact strategy.

Severity: can I keep driving?

Drive with caution, fix soon

Sources disagree on how urgent this is. OBD-Codes.com describes P2002 as often a 'soft' code that can clear itself once the DPF regenerates (burns off its soot), while RepairPal rates P2002 as 'Urgent'. Both agree it shouldn't be ignored: OBD-Codes.com notes that if the DPF isn't cleared, the engine computer can put the vehicle into limp-home mode, and repeated regeneration attempts can dilute engine oil with fuel. Get it checked soon, and sooner if you notice limp mode, sluggish acceleration or a rising oil level.

Common symptoms

Check engine light on, sometimes coming and going as the DPF regenerates
Lower fuel economy while the engine tries to raise exhaust temperature
Sluggish acceleration
Engine oil diluted by fuel (oil level may rise) from regeneration attempts
Limp-home mode if the DPF isn't cleared

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Soot buildup from too much low-speed or short-trip driving
Diesel particulate filter failure or damage
Air or exhaust leak ahead of the DPF throwing off the sensor readings
Dirty or out-of-calibration mass airflow (MAF) sensor
Faulty DPF pressure sensors, wiring or connectors
Engine computer faults or components that prevent regeneration
High-sulfur fuel clogging the filter
Dirty air filter, or aftermarket intake/exhaust modifications

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read all stored codes and freeze-frame data, and fix related codes (MAF, EGR, pressure sensor) first.
Check the DPF mounting and exhaust connections on Bank 1 for leaks or looseness.
Inspect the DPF differential pressure sensor(s) and their hoses and wiring. Look for burnt wires, loose or corroded connectors, bent pins, and wires resting on the hot DPF.
Check the engine air filter and replace it if dirty.
If everything looks good and the vehicle drives normally, a sustained highway drive (OBD-Codes.com suggests about 30 minutes) can raise exhaust temperature enough to regenerate the filter. Follow your owner's manual on regeneration.
If you've installed a cold air intake or aftermarket exhaust, OBD-Codes.com suggests refitting the stock part to see if the code clears.

Typical fixes

Complete a DPF regeneration (driven or shop-forced with a scan tool)
Repair air or exhaust leaks ahead of the DPF
Clean or replace the MAF sensor
Repair DPF pressure sensor wiring or replace a faulty sensor
Replace a damaged or failed DPF
Change the engine oil if it's been diluted by fuel

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The code returns after a highway drive or regeneration attempt
The vehicle goes into limp-home mode
A shop scan tool is needed to watch the DPF sensors live and see whether the computer is attempting regeneration
The vehicle is under emissions warranty

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Will P2002 clear on its own?

Sometimes. OBD-Codes.com describes it as a 'soft' code that can clear itself once the DPF successfully regenerates. If it keeps coming back, have the sensors and regeneration checked.

What's the difference between P2002 and P2003?

They're the same fault. P2002 is Bank 1 (the side with cylinder 1) and P2003 is Bank 2.

Should I just remove the DPF?

We don't recommend it. One source mentions deleting the DPF where legal, but removing emissions equipment can break emissions laws and affect your warranty. Check your local rules and stick with a proper repair.

Is P2002 urgent?

Sources differ: RepairPal rates it 'Urgent', while OBD-Codes.com says it's often temporary. Because it can lead to limp mode and oil dilution, get it checked soon.

Sources

Last reviewed 2026-10-21. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.