Ash is the unknown killer, says DPF experts
Ash accumulates in the filter over, time, and must be periodically and physically removed
Particulate matter is a complex mixture of small particles and droplets and are considered to feature two main components – soot and ash.
The advice comes from a DPF refurbishing company, who claim that vehicles fitted with DPFs are most likely to become due to ash accumulation.
“You will always hear people talking about soot blockages but never ash.”
Ash is a standard byproduct of the combustion process that take place in the engine but, unlike soot, it accumulates in filters and cannot be burned off by a simple regeneration processes.
“You will hear many references where a forced regen has been carried out, to only find the customer returning after a few days or weeks with the same issue.
“In most cases, this will be the result of ash accumulation.
“If the vehicle’s ash accumulation is high, then the OBD system will register an increase in back pressure on the DPF.”
The OBD will trigger a regeneration in the DPF and regenerations will become more frequent as the back pressure continues to build up over time and eventually the vehicle may enter limp-home mode.
By assessing the mileage and information gathered by the OBD it should be possible to determine whether a DPF is blocked with soot, for which a forced regeneration would be sufficient, or ash, in which case the DPF requires removal and cleaning or replacement.