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P2002 – Diesel Particulate Filter Efficiency Below Threshold (Bank 1) (OBD2)

Fault code P2002 means "Diesel Particulate Filter Efficiency Below Threshold (Bank 1)". Below are the real-world causes, step-by-step tests and OEM part numbers.

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P2002 quick summary

Fault codeP2002
MeaningDiesel Particulate Filter Efficiency Below Threshold (Bank 1)
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityMedium
Can I drive?Yes in most cases, but the car may fail the emissions test and the ECU can limit power. Do not ignore it – a cracked DPF lets soot out of the exhaust.
Repair cost€80 – €3,000

Symptoms of P2002

  • Check Engine / DPF warning light on
  • Black soot at the tailpipe (cracked or damaged DPF)
  • Failed emissions / smoke test
  • Possible limp mode or reduced power
  • Regeneration starts too often or never

Most common causes of P2002 (most likely first)

Mechanic's Pro Tip

P2002 usually means the measured differential pressure across the DPF is LOWER than expected – the ECU thinks soot is passing straight through. Before condemning the filter, check the two small hoses of the differential pressure sensor: a cracked, swapped or disconnected hose and a faulty sensor are the cheapest and most common fixes. If the hoses and sensor are fine, the DPF ceramic may be cracked.

  1. 1.Cracked, split or damaged hose to the DPF differential pressure sensor

    Most likely

  2. 2.Faulty differential pressure sensor

  3. 3.Cracked or melted DPF ceramic (after uncontrolled regeneration)

  4. 4.Exhaust leak before the DPF

  5. 5.DPF removed or tampered with

  6. 6.Software or soot/ash model needing a reset after DPF replacement

Step-by-step diagnostic guide

  1. 1

    Read all codes; check for related DPF, EGR and sensor codes.

  2. 2

    With the engine off, the differential pressure value should be close to 0 mbar. At idle and when revving, it should rise clearly – a value that barely changes points to a hose or sensor fault, or a cracked DPF.

  3. 3

    Inspect both sensor hoses along their full length for cracks, melting, blockage and correct connection (inlet/outlet not swapped).

  4. 4

    Check the exhaust for leaks between the engine and the DPF.

  5. 5

    Look into the tailpipe: black soot inside a car with a DPF points to a damaged filter.

  6. 6

    After replacing the DPF or sensor, carry out the required adaptations (e.g. reset the soot/ash values) with a suitable scan tool.

Frequently asked questions

Can I just clean the DPF?

Cleaning helps when the filter is blocked, but P2002 more often means the filter is damaged or the sensor reading is wrong. A cracked DPF cannot be cleaned and must be replaced.

How much does it cost to fix P2002?

A differential pressure sensor costs about 80–200 € fitted. Hoses cost very little. Professional DPF cleaning costs about 200–600 €, an aftermarket DPF about 500–1,500 € and an original DPF 1,000–3,000 €.

Is removing the DPF an option?

No. Removing the DPF is illegal for road use in the EU, the car fails inspection and insurance cover can be affected.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.