P2002: Diesel Particulate Filter Efficiency Below Threshold (Bank 1)

P2002 means the engine computer has decided the diesel particulate filter is no longer trapping soot as well as it should. Depending on the engine, it judges this from a soot sensor after the filter or from a pressure difference across the filter that is lower than expected for the exhaust flow, so the usual causes are a cracked or melted filter, a filter that has been removed or emptied, or a pressure sensor or hose fault that makes the filter look that way. A filter clogged with soot normally sets different codes, such as P2463 or P244B, although some manufacturers, VW group among them, use this code more broadly. P2002 is the code for bank 1, which on most diesels is the only particulate filter; P2003 is the bank 2 twin on engines with two filters.

P2002 is a emissions-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P2002 and illuminates the check engine light.

If your vehicle has triggered P2002, you may notice one or more of these symptoms:

• Check engine light on
• Often no change in how the car drives
• Black soot at the tailpipe or on the back of the car, most visible under hard acceleration
• Exhaust emissions check failed at a roadworthiness test
• DPF warning light or reduced power on some models
• P244A or P226D stored at the same time on some cars

Here are the most common causes of P2002:

No - address this immediately. Drive gently and only as far as a workshop. A cracked or damaged filter lets soot out of the exhaust and can fail an emissions check, and on some makes, VW group cars among them, this code also covers a filter that regeneration has not cleared, where backpressure builds and the engine can drop into reduced power. Have the cause found within days, and do not switch off in the middle of a regeneration.

Follow these steps to pinpoint the root cause of P2002:

1. Read all stored codes and the freeze frame with an OBD2 reader. Note whether P244A (pressure too low), P226D (filter missing), P244B or P2463 (pressure too high, soot build-up) sit alongside P2002, because they say whether the filter looks empty or full. A generic OBD2 reader can show these codes, the freeze frame and standard live data, but on most cars not the pressure across the filter, the soot load or the regeneration history, and it cannot run a forced regeneration or an adaptation: those need manufacturer-level software or a workshop.
2. Inspect the pressure sensor hoses and pipes for splits, melted sections, blockage or a loose end, and check that the upstream and downstream hoses are on the right ports. A hose that no longer sees the pressure ahead of the filter makes the filter look cracked or empty while it is fine.
3. Check the exhaust for leaks between the engine and the filter, which also lower the pressure the sensor sees.
4. With manufacturer-level software, read the pressure across the filter at several engine speeds and loads and compare it with the specification for that engine. With the hoses and sensor proven good, a reading well below specification points to a cracked, melted or missing filter; one well above it points to a loaded filter instead.
5. Look for soot where there should be none: a filter that works leaves the tailpipe and the pipe after it largely clean. A workshop can hold a clean cloth over the tailpipe while the engine is revved to see whether soot is getting through; this test is not meaningful straight after a regeneration, when an empty filter traps less.
6. On makes that use P2002 for a loaded filter, such as VW group diesels, a forced regeneration with manufacturer-level software is a legitimate next step once the sensor and hoses are proven good. If it does not bring the pressure back into range, the filter needs cleaning off the car or replacing.
7. A cracked or melted filter has to be replaced; cleaning removes soot and ash but cannot repair the substrate. Before fitting a new one, find what overheated or overloaded the old one (leaking injectors, a faulty exhaust fuel injector, repeatedly interrupted regenerations) and confirm the engine oil meets the low-ash specification, then have any adaptation the engine computer requires done with manufacturer-level software.

Repair costs for P2002 vary depending on the root cause and your vehicle. Here are typical estimates:

P2002 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

These codes are often seen alongside P2002 or indicate related issues: