1.6 tdci starts in limp mode, engine braking makes it normal

[Daneontheroad]

My wife's 2008 1.6 tdci C-Max has begun starting in limp mode without an engine fault indicated, regardless of engine temperature. It will stubbornly stay in limp mode (my longest test with constant speed was 15 km from a warm start). If, however, I get it to normal temperature and then do an engine brake from, say 50 km/h to maybe 20 in 3.rd gear, the engine awakens and will pull better. After a few minutes the engine performs nominally. This behaviour also happens after a very short stop, and then the engine braking will immediately make things fine bc the engine is warm. And after the fix it never falls back into limp mode - that is, until I stop the engine.

The turbo was changed 3.000 km ago, the fuel filter is almost new, and when the problem is sorted the car is quite quick. Something must be sticking, methinks, either physically (EGR?) or software-wise. Or maybe there is oil or something in a tube that needs to be blown back. I dunno.

Oh, and only a few 100's km ago I complained to my mechanic that the car leaked exhaust after the turbo swap, and it turns out he had not assembled the DPF correctly. Something was leaking and he fixed it second time around, but then soon after, this problem arose. Coincidence? I have no idea.

Please, if you have any thoughts I would love to hear them. Cheers.
j.

[pragmatix]

Maybe the DPF sensor pies are the wrong way round that's where I would start..