Cause
Incorrect engine oil specification used
Oil that meets the viscosity but not the manufacturer's approval standard. On a vehicle with a particulate filter this matters more than viscosity does: low-ash oil exists because ordinary additives leave incombustible ash in the filter, permanently.
Ordinary oil shortens a filter's life dramatically. Ash accumulates far faster than designed, the filter reaches its restriction limit well before its expected mileage, and no amount of regeneration helps because ash does not burn. A filter ash-loaded early is worth taking to the oil rather than to the engine. The approval code is what matters, not the grade — two oils of identical viscosity can differ entirely in ash content, and the code is printed on the container beside the specification.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (1)
Codes where this is a likely explanation first, rather than merely a possible one.
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