Hi all. I have a 54 plate Pic 2.0 HDi 90HP (exclusive) that is starting to drive me bonkers with the P0400 range of codes / Engine fault message.
Long story short.
EGR valve removed & cleaned. Proven to open fully under vacuum, snapping shut again after. EGR pressure converter checked & operates. Replaced MAF for a new pattern part
I have tried the pulling the pipe & plugging it trick, fault codes created within 4 miles driving
I have blanked off the EGR valve fully, fault light & lack of air flow code created. Drilled a 4mm hole in the blanking plate to allow a bleed of air for the MAF to recognise as an air flow, still lack of flow code created. plate removed fully again.
Unfortunately the car is probably the change point where the management system will not allow you to just disconnect the EGR.
Strangely the issue seems to be a warm/hot weather problem, no faults at all during the colder days & winter.
I am fortunate enough to have a neighbour who has access to a trade rated OBD reader (but do not wish to push our good terms too far by continually asking for help)
I had read on the forums & elsewhere of the engine air temp sensor causing issues but I am unable to locate this on my engine, In the MAF I believe.
When using the diagnostic tool we did notice that the EGR was being recognised as opening under acceleration & closing at idle. The air flow (kilo pastels??) should had climbed as the engine revs increased but it was noted that the flow dropped & then picked up again (as if the graph dipped instead of climbing on a steady slope up)
I now have the code P0400, generic exhaust gas recirculation flow & P0402 exhaust excessive gas flow, hinting that the EGR is fully open.
Here's hoping that someone out there recognises this series of events & has some pointers for me to try next.
All in I think its a great car, a little slow & at times gutless, this may be due to the EGR related issue but it does all I need.
Many thanks for any return posts.