Diesel Particulate Filter Efficiency Below Threshold Bank 1
Your diesel engine's particulate filter isn't trapping exhaust soot effectively, like a clogged air filter that lets dirt through. The engine computer detected the filter efficiency dropped below acceptable levels.
The ECU monitors differential pressure across the DPF using pressure sensors before and after the filter. When exhaust backpressure exceeds safe thresholds or regeneration cycles fail repeatedly, the filter efficiency calculation drops below minimum limits, triggering the fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| DPF Efficiency Rating | ≥85% soot capture | <85% soot capture |
| Differential Pressure | <150 mbar | >150 mbar sustained |
Code P2002 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P2002 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.