Code classification
What this reference means
The control module recorded a condition matching Diesel Particulate Filter Efficiency Below Threshold Bank 1. This identifies the monitored condition, not a guaranteed failed part. Software version, operating conditions and related codes must be considered together.
Monitored system: Diesel particulate filter efficiency monitoring
Possible symptoms
- Malfunction indicator lamp
- Regeneration may be inhibited or requested frequently
- Reduced-power operation on some platforms
Possible causes to investigate
- Exhaust leak upstream of or near the monitored filter
- Incorrect differential-pressure signal, blocked hoses or wiring fault
- Excessive soot loading or ash accumulation
- Temperature-sensor or regeneration-control fault
- Combustion, boost, EGR or injector problem increasing particulate output
- Damaged or unsuitable particulate filter
A list of possible causes is not a parts-replacement instruction. Test the circuit and system under the code's enabling conditions.
Workshop diagnostic sequence
- 01
Preserve freeze-frame, pending codes and regeneration history.
- 02
Inspect the exhaust for leaks and verify pressure hoses are correctly routed and clear.
- 03
Compare differential pressure with key-on/engine-off and controlled engine-speed conditions.
- 04
Review soot and ash estimates, exhaust temperatures and regeneration prerequisites.
- 05
Diagnose engine faults that can increase particulate production before judging the filter.
- 06
Repair the cause, complete the OEM verification procedure and confirm the monitor passes.
Related technical context
Compliance
Safety and emissions-related faults must never be hidden on a road vehicle. Diagnose and repair the root cause. Required OBD and emissions systems must remain operational where the applicable law requires them.