P2002–P2003 Particulate Filter Efficiency Below Threshold Bank 1
The part still works but no longer well enough to meet its target - worn out rather than broken.
Can you drive it? The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
P2002 | Particulate Filter Efficiency Below Threshold Bank 1 | Investigate soon |
P2003 | Particulate Filter Efficiency Below Threshold Bank 2 | Investigate soon |
The definition
P2002: Particulate Filter Efficiency Below Threshold Bank 1.
P2002 is a manufacturer-specific powertrain code (the engine or gearbox). Its meaning is set by the carmaker rather than by the SAE standard, so a generic OBD-II reader will often show it as an unknown code or misread it.
What to check first
Cheapest and fastest checks first:
- Confirm the sensors either side are both healthy before condemning the expensive part - a lazy rear sensor mimics this fault.
- Check for exhaust leaks upstream, which let extra air in and skew the reading.
What actually causes this on a VAG
This is the diesel particulate filter. Your ECU judges whether the filter is doing its job mainly from a differential pressure sensor, which measures the difference in exhaust pressure before and after the filter, plus its own internal model of how much soot should have collected in there. P2002 means those two don't agree - the restriction the ECU actually measures isn't what a healthy, correctly loaded filter should be producing. Most often that means it's seeing too little, which points at a filter that's cracked, gutted or leaking, or at a sensor and its pipework telling fibs. It can also appear on a filter that's genuinely worn out or ash-loaded, though on VAG diesels a simply blocked filter more usually brings its own soot-loading or pressure-too-high codes with it - so read everything that's stored before deciding which way this one is pointing. The car may drop into reduced power, or it may just sit there with the light on.
Most likely causes, in order
- The pressure sensor and its two small pipes. The sensor lives under the bonnet with two thin hoses running down to the exhaust, and those pipes crack, chafe through, soot up solid or get swapped over after other work. With the engine idling the measured pressure difference should be close to nothing, so this is a few minutes with live data and a good look at both pipes and their unions.
- An exhaust leak around the filter. A blowing gasket, cracked pipe or leaking clamp between the two sensing points bleeds away the very pressure the sensor is trying to measure, and the ECU reads that as a filter doing nothing. Listen for a blow from cold and look for soot streaks around the joints.
- Something upstream making far more soot than normal. A leaking injector, an EGR valve stuck open, a boost leak or failed glow plugs will all overwhelm the filter and pull the ECU's soot model away from reality. Read everything else that's stored before laying a finger on the filter - this is both cheaper to find and the thing that decides whether a new filter would survive.
- The filter itself damaged, ash-loaded or gutted. The internal honeycomb can be cracked or partly melted by repeated hot regenerations, and some cars have simply had the filter hollowed out by a previous owner. The ash and soot mass figures and the regeneration history stored in the ECU, plus a look up the pipe, will usually settle it.
Worth knowing: Never buy a DPF as the first move - check the pressure sensor, its pipes and the exhaust joints first, and fix whatever is producing the extra soot, because fitting a new filter to an engine that's still sooting heavily just kills the new one. Also worth knowing: in the UK, removing a DPF makes the car illegal to use on the road and is an automatic MOT failure, and most other European countries take a similar line.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.
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Common questions
What does P2002 mean?
P2002 means Particulate Filter Efficiency Below Threshold Bank 1. The part still works but no longer well enough to meet its target - worn out rather than broken.
Can I drive with P2002?
The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.