P2003: Diesel Particulate Filter Efficiency Below Threshold (Bank 2)

P2003 means the engine computer has decided the diesel particulate filter on bank 2 is no longer trapping soot as well as it should. Depending on the engine, it judges this from a pressure difference across that filter that is lower than expected for the exhaust flow, or from a soot sensor after the filter, 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 use this code more broadly. Bank 2 only exists on V-engine diesels with one particulate filter per cylinder bank, such as some V8 and V12 diesels; on single-filter diesels the matching code is P2002.

P2003 is a emissions-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P2003 and illuminates the check engine light.

If your vehicle has triggered P2003, 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
• P2002 or P244A stored at the same time on some cars

Here are the most common causes of P2003:

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 get the car rejected at an emissions check, depending on the country's rules, and on some makes this code also covers a bank 2 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 P2003:

1. Read all stored codes and the freeze frame with an OBD2 reader. Note whether P2002 (bank 1), P244A (pressure too low), P244B or P2463 (pressure too high, soot build-up) sit alongside P2003, 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 each 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. Confirm the engine really has two particulate filters. Bank 2 is the cylinder bank that does not contain cylinder 1; on a twin-filter V8 or V12 each bank has its own filter, pressure sensor and temperature sensors. A single-filter diesel should report P2002 instead.
3. Inspect the bank 2 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.
4. Check the exhaust for leaks between the engine and the bank 2 filter, which also lower the pressure the sensor sees.
5. With manufacturer-level software, compare the pressure across the bank 2 filter with bank 1 at the same engine speed and load. With the hoses and sensor proven good, a much lower bank 2 reading points to a cracked, melted or missing filter; a much higher one points to a loaded filter instead.
6. Look for soot where there should be none: a filter that works leaves the tailpipe and the pipe after it largely clean, and a workshop can hold a clean cloth over the tailpipe while the engine is revved to see whether soot is getting through.
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 P2003 vary depending on the root cause and your vehicle. Here are typical estimates:

P2003 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

These codes are often seen alongside P2003 or indicate related issues: