P0638 from new pierburg air control flap

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P0638 from new pierburg air control flap


New member
Jun 15, 2023
Hi all,, I have been working through a sticky issue with my 3 litre multijet Ducato Motorhome.
bought the motorhome shortly after the previous owner had got a brand new pierburg air control flap fitted and it’s now throwing a p0638 fault code again!

Few things I have noticed while testing
There was some wiring issues back further the loom goin to this valve but an auto electrician as assured me that these are all correct!

If I disconnect the plug connection fully, I have the fault code p0638 and have no power with intermittent throttle response!
If I connect the valve and only disconnect the earth wire feeding the valve,, the valve remains unoperational but the code goes out and full power is restored! I ended up goin to wales with it like that last weekend!

If I connect the three wires,, and disconnect either the ecu feed or the 12 volt feed,, I get the fault code straight away!

My question is,, how come just removing the earth wire stops the valve from working but I have no code and I still have full power??

If leave the new valve fully connected,, and extinguish the fault code and start the engine,, after 20-30 seconds can hear the valve operate and throws up the fault code!

Is this new valve faulty or what causes the engine code to be generated so quickly

Hope someone can help me shed some light on this