I've been experiencing occasional loss of power while driving at low speed (about 30 - 40km/h) when engine is cold. Previously had CPS trouble and had it replaced a few months back with another genuine unit. I feel I have a good handle on what failing CPS feels like, and I don't think this is it.

Earlier today replaced the fuel filter. The filter in the photos is 2.5 years old and has traveled 20,000 km. I've opened up the filter housing to see what it looks like inside. Looking at the state of the filter material any chance it could have been responsible for the occasional losses of power?

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I don’t know but it doesn’t look too bad to me ?

Thanks for your reply. I've never seen inside one of these before so wasn't sure how dirty is dirty. MY10 TD4 SE Auto

Since there's still a bit of white in spots I don't think it's too bad. Those kind of elements are designed so that as parts of the element get dirty and more restrictive to flow, the flow naturally shifts to cleaner areas.

I assume the particles on the end are from cutting the case open?

Yes, those are shavings from cutting the case open.

Prior to replacing the fuel filter I noticed quite a few air bubbles in the clear lines making their way to the high pressure pump. I read somewhere that air in fuel line can be bad and could cause rough running. So I went about unplugging all 4 lines, checking O rings etc. and plugging them back in - all to not avail, those air bubbles kept on traveling past, right before my eyes.

But once the filter was replaced, for 3 days now, no air bubbles. Both filters were genuine. That's all I ever use. The only thing that is different is the way I primed it this time. Usually I attach priming bulb to the exit / filtered fuel end of the fuel filter (with all other lines attached but the one that goes to the high pressure pump). I pump until the fuel comes out, and when it does I disconnect the primer and re-attache the last line (the one that goes to the high pressure pump).

On this occasion I decided to prime from the inlet side. The primer bulb is attached to the inlet (dirty fuel) side with all the other lines connected to the filter as normal. And this time no bubbles, for 3 days now. Not sure if this is just coincidence or is it in fact better to "push" fuel through the filter when priming vs "pulling" fuel out the filtered end.

Any thoughts? MY10 TD4 SE Auto

What are the chances of a genuine fuel filter being faulty, could it have been that? MY10 TD4 SE Auto