Cause
Faulty exhaust gas differential pressure sensor
The sensor that reads the pressure drop across the particulate filter — the filter's fuel gauge, since soot load is inferred from how hard the exhaust pushes to get through. Every regeneration is scheduled from this number, which is what makes its failures consequential out of proportion to its price: a sensor lying low teaches the module the filter is empty, so regenerations stop and the filter fills toward the forced-regeneration ladder; lying high burns fuel on regenerations nothing needed.
Its plumbing fails more than it does. Two thin hoses tap the exhaust either side of the filter, and they crack with heat, block with soot, and get refitted swapped after exhaust work — each producing believable wrong readings the sensor faithfully reports. The free cross-checks: zero difference with the engine off, small and steady at warm idle, climbing with load. A reading that ignores the engine has convicted the plumbing, not the sensor — and either is a fraction of the filter this family protects.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (11)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2002 Particulate Filter Efficiency Below Threshold — Bank 1 Likely for this code High
- P2003 Particulate Filter Efficiency Below Threshold — Bank 2 Likely for this code High
- P226D Particulate Filter Deteriorated/Missing Substrate Bank 1 Likely for this code High
- P244A Particulate Filter Differential Pressure Too Low Bank 1 Likely for this code Moderate
- P0401 Exhaust Gas Recirculation A Flow Insufficient Detected Moderate
- P0402 Exhaust Gas Recirculation A Flow Excessive Detected Moderate
- P0486 Exhaust Gas Recirculation Sensor B Circuit Low
- P242F Particulate Filter Restriction - Ash Accumulation Bank 1 High
- P2452 Particulate Filter Pressure Sensor A Circuit Moderate
- P2453 Particulate Filter Pressure Sensor A Circuit Range/Performance Moderate
- P2464 Particulate Filter Differential Pressure Too Low — Bank 2 Moderate
Information, not instruction
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