These Gasoline Particle Filters (GPF) or here called Otto Filters are beginning to raise heads due to new regulations. Here are just a few writeups just as a Heads Up on what could be encountered especially regarding the Problem Nissan 1,2L DIG engine which looks like being replaced soon by a 1,3L - Dave
GASOLINE PARTICULATE FILTER (GPF)
Up until now, petrol engines haven’t been required to fit the equivalent Gasoline Particulate Filter (GPF), which means that all of the direct injection petrol cars currently circulating are throwing PM out the back, and we mean a significant amount. You can’t see it because it is very fine, and that is worrying because it is the ultra-fine portion of PM that is associated with the worst health impacts, there is no safe lower limit, in other words, any amount of petrol or diesel PM that you breath in has an adverse health impact and that sounds like something you need to avoid.
As part of the efforts to stop another VW-type scandal, all new models have to undergo extra tests and from September 2018 every new car will be subjected to these tests. PM limits now for the first time apply to direct injection petrol engines which is fantastic news. In announcing the new standards the EU said that GPF would be required to hit the new limits, but not all car manufacturers did agree. It is hoped that all manufacturers will see sense and fit GPF as standard. Each filter costs around £25, requires no maintenance, doesn’t increase fuel consumption and is simpler than a DPF because it won’t clog up in urban running as the exhaust from a petrol engine is hot enough to allow the filter to clean itself without any extra help.
https://www.greencarguide.co.uk/feature ... ilter-gpf/
GPFs look very similar to DPFs and, generally speaking, work in a similar way. The filter has a honeycomb structure, usually made from cordierite, a synthetic ceramic, with alternately sealed inlet and outlet channels. The exhaust gas is forced to flow through the porous filter substrate, which traps the soot. At about 200 to 350 channels per square inch, the canal density of the GPF is nearly the same as a DPF. The major difference between the two types of filter is that the porosity of the GPF is higher because the substrate is lighter. Although this allows the gas to move more easily across the substrate, it also means the GPF is more fragile than a DPF.
http://www.infineuminsight.com/insight/ ... te-filters
http://ac.umicore.com/en/technologies/g ... te-filter/