P243C: Repeatedly short diesel particulate-filter regeneration intervals

P243C is cataloged as particulate-filter regeneration frequency, bank 2. Mazda's SKYACTIV-D page describes abnormally short distance between regenerations without identifying a bank-2 hardware arrangement; this article is a source-scoped Mazda example, not proof of that generic bank mapping.

Distinguish soot production from failed removal

The source describes three repeated events involving regeneration intervals of 50 km or less and an excessive target particulate accumulation relative to the amount actually removed. Possible causes include abnormal combustion producing too much soot, an exhaust-pressure sensor problem, high DPF pressure difference and soot that regeneration does not remove.

Mazda compares the particulate-accumulation and soot-generation data before selecting the next branch. It then considers the pressure sensor and the result of a controlled regeneration, or investigates fuel-injection learning, fuel supply, EGR, intake shutter and turbocharger behavior. Repeated regeneration therefore does not by itself prove that the filter needs replacement.

The response to regeneration is evidence

Whether the calculated accumulation falls toward zero after an appropriate completed regeneration changes the diagnostic conclusion. Equally, a combustion problem that creates excess soot must be addressed even if the filter can be cleaned.

Forced regeneration and injection-learning procedures require qualified supervision and the exact service conditions. Preserve the interval history and both particulate data values before resetting anything. The bank-label mismatch remains an applicability limitation; confirm the actual vehicle's DTC definition and aftertreatment layout.

Documented application

Mazda3 workshop manual 01/2019 onward, d9n1-1a-22d_ver10; PCM (SKYACTIV-D). Verify exact vehicle specification; this is a Mazda application example. Mazda factory diagnostic page, mirrored by CHARM.