Get it Right – DPF Remanufacturing to Meet Stringent Emissions Standards
As lifecycle-based emissions regulations take hold across major markets, truck and bus manufacturers must rethink how they manage the diesel particulate filter (DPF). Remanufacturing is a cost-effective solution, but beware not all remanufacturing is equal, and you must ensure compliance.
For years the DPF has done its job, trapping soot and ash from the exhaust stream of heavy goods vehicles (HGVs) and public service vehicles (PSVs) without drawing much attention from anyone outside the workshop. But a new wave of regulations, such as Euro VII, has made the DPF a major compliance issue for OEMs.
Tier 1 remanufacturers such as ourselves are responding by scaling up cleaning and inspection technology to meet these new compliance needs. At Eminox Group of Companies, for example, we have facilities across the UK, Europe, and India with joint ventures in North America and Japan.
Lifetime accountability
And the shift in regulatory focus is significant. Euro VII monitors compliance across a vehicle’s entire operating life rather than simply checking it once at the point of type-approval. And California’s “heavy duty omnibus” rule cuts vehicle Nox limits by 90% for new large goods vehicles between 2024 and 2031, with tougher in use testing across real-world driving conditions.
For OEMs it means that a DPF that underperforms after 2 or 3 years is not just a warranty issue, it is a regulatory breach. Suddenly the ongoing DPF condition is vital for both engineering and compliance teams.
Managing the whole exhaust system
Understanding the risk begins with the exhaust after treatment chain.
Modern diesel HGVs and PSVs typically combine three systems:
- a diesel oxidation catalyst (DOC) that converts carbon monoxide and hydrocarbons into less harmful compounds and preps nitrogen oxide for downstream use
- the DPF, which traps particulate matter
- and a selective catalytic reduction (SCR) system that uses a urea solution to strip nitrogen oxides from the exhaust stream
These three components are interdependent. A correctly operating DOC supports efficient DPF regeneration, and a clean properly functioning DPF reduces back pressure and protects the downstream SCR catalyst. It means that DPF servicing needs to be part of a holistic exhaust system strategy.
DPF remanufacturing getting it right
To meet lifecycle monitored compliance requirements, OEMs need to ensure the quality and consistency of DPF remanufacturing or face the cost of new part replacement. To comply, remanufactured units must restore near-new flow and back-pressure performance, control residual ash, and demonstrate emissions capability under documented, repeatable test conditions.
A failed remanufactured unit costs a lot more to replace than the cost of a properly managed cleaning process, so check the remanufacturer’s yield rate. This is the proportion of units that they successfully retore from a given batch, which will depend on how effectively they remove the soot and ash from the substrate.
The cleaning technology matters
For OEMs choosing the right remanufacturing partner is vital. Not all DPF cleaning is the same and this will affect whether the filter is genuinely restored to “like new” or merely appears serviceable.
Lower cost and older approaches such as “air knife” cleaning that only use compressed air will leave uneven residual deposits. You will see marks across the substrate face, which means that soot and ash have been displaced but not fully purged from the channel walls. Incomplete cleaning will lead to higher back pressure, inefficient filtration, or even premature failure when it is back in service.
Water assisted processes avoid this. Our patented Xpurge system, for example, fills the DPF’s cells with de-ionised water before driving a pulse of compressed air through the filter. The water forces the compressed air across the porous cell walls to remove soot and ash from the inlet channels rather than simply knocking loose surface deposits.
A related process, Flexpurge®, applies the same water-and-air mechanism from the outlet side for filter geometries that call for it.
This dislodged contaminant stays suspended in the water, so nothing is released into the atmosphere. The process means we will capture and safely dispose the residue.
Our method is 30% more effective than compressed air or other water-based systems on the market. It restores filters to as much as 99% of their original OEM performance.
Better cleaning means you will end up with more remanufactured DPF units that meet modern compliance requirements. It will keep failure rates down and protect OEMs from the higher cost of replacing units that do not pass.
In addition, aggressive cleaning or using the wrong method can strip or damage the coating that gives the DPF, and the associated SCR, their catalytic function.
OEMs need to see a repeatable, non-destructive result before they specify a cleaning process in a warranted exchange programme.
It means that internal inspection also needs to be part of the process. Our Veritex process produces images of the substrate to check for cracks or defects and will produce a verified digital record. This makes the workshop process auditable to provide the documentation that lifecycle regimes such as Euro VII demand.
ESG
Remanufacturing a DPF is better for the environment than using a new part, since it significantly reduces the embodied carbon. One study found that remanufactured units had roughly 8.3 kg CO₂e, against approximately 126 kg CO₂e for a new equivalent.
Restored and verified DPFs also reduce the frequency of fuel regeneration cycles to reduce CO2 emissions over a vehicle’s life and the right, regulated cleaning process captures particulates so that they are not released into the atmosphere.
Tightening emissions regulations and the growing need to report on carbon reduction means that the quality of DPF remanufacturing is a mainstream servicing requirement. When seeking the right partner for remanufacturing the cleaning process really matters.
Get it wrong and it will cost the OEM not only in failed units, but in warranty claims and reputation though failed compliance. Get it right and OEMs can keep their fleet moving, save cost, and build an auditable compliance trail that regulators now expect.
