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Why is my car trying to regenerate constantly after the DPF was cleaned?

I have a Ford Focus 1.5 diesel, which I bought very recently second-hand from a main dealer. A couple of weeks ago a fault code indicated a blocked DPF. The garage cleared the DPF under warranty, but recently I have noticed that every time I use the car it is attempting to regenerate, i.e. it has a high idle speed, start stop doesn't work, poor fuel economy. My daily commute is a 44-mile round trip and the car got a 100-mile motorway blast just the other day. I checked the oil and the dipstick shows the level to be too high, I understand that failed regens dump diesel back into the sump and degrade the oil. My driving style cannot be causing this issue. Am I looking at a faulty sensor of some sort?

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It's trying to actively regenerate too often and I guess you are probably switching off the engine mid active regen, which is what dumps the post-injected diesel into the sump. The engine might work better using Superdiesel. It's very important to keep engine revs above 1500 until the engine is fully heated up because that creates less soot. More than 2000rpm helps to promote passive regen. Don't think that because it's a diesel you can drop it into higher gears at 1000rpm.
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