P2002 code: diesel particulate filter (DPF) efficiency below threshold

When the code is set

The differential pressure sensor measures the pressure difference before and after the filter; some cars also have a particulate sensor after the filter. If the values fall outside the expected range on several checks in a row, for example a pressure difference that is too low and points to a cracked filter, the ECM stores P2002.

Symptoms

• The check engine light or the DPF warning light is on.
• Less power and slower acceleration.
• Higher fuel consumption.
• More frequent or failed DPF regenerations.
• Limp mode.

Common causes

• Lots of short journeys, on which the soot in the filter cannot burn off.
• A faulty differential pressure sensor or damaged, disconnected pipes to it.
• An air or exhaust leak ahead of the filter.
• A cracked or melted filter.
• An unsuitable or wrongly fitted replacement filter.
• Engine control module software (on some models).

How to find the cause

A mechanic usually works like this:

1. Read all codes and freeze frame data.
2. Check the differential pressure sensor and its pipes.
3. Look for exhaust leaks ahead of the filter.
4. Start a DPF regeneration with a diagnostic tool and watch the readings.
5. Inspect or replace the filter only once other causes are ruled out.

Notes by make

Audi

In the US, Audi issued a service bulletin for codes P200200 and P246300 on 2014–2015 A6, A7, A8 and Q5 TDI models: the cause was engine control module software that did not correctly handle a brief pressure rise in the filter. The fix is a software update, not new parts. A workshop can check whether this applies to your car.

Other ways the code is written

Scan tools and workshop printouts sometimes show the code with extra characters:

• P200200

Related codes

• P2463 DPF soot restriction, bank 1
• P0401 Low exhaust gas recirculation flow
• P0299 Turbo boost pressure too low

Frequently asked questions