Error code U1025 turbocharger boost communication line

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Nov 27, 2019
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Hi guys.
I have a 2015 navara d40 Spain build Vsk model 2.5 turbo diesel 4x2
Car was running just fine. Engine light came on so I just did the usual tighten up the petrol cap and it went away the next day. Happend twice.
Now yesterday the engine light came on again but this time lost power.
It bogs down above 2000rpm
I checked hoses,
Cleaned MAF sensor and vacuum valve (I think it’s the boost solenoid) as on mine it’s not next to the alternator and airbox it was under the engin cover up top.
This error code pops up U1025 turbocharger boost communication line and just wondering if anyone has had this issue before?
Thanks in advance guys
Any help would be great


Oct 3, 2009
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Mid Coast Region, NSW, Australia
Welcome to the forum.

I haven't looked under the bonnet of a 2015 D40, but I am fairly sure that in around 2012 or so they changed to an electronic actuator control because the vacuum-operated one had issues. But, maybe they changed back. Those of us with older cars with vac-operated units have had BCS failures as well as vac leaks. They wouldn't put our cars into limp mode, but your car will have later software too and they might have included a boost fault in the "limp mode" list. That makes some sense, because a boost fault means much less air, which means more soot and therefore more deposits in the exhaust.

If you suspect the boost control solenoid (if your turbo is vac-controlled), find the vac hose that comes from the vac pump and take it off the BCS, and connect this hose to the top of the turbocharger's actuator. Drive the car - gently, no harsh acceleration - and see if it goes over 2,000rpm. Be careful - if your turbo is vac operated, what you are doing here is opening the vanes of the turbo fully, so it provides maximum boost from the beginning (as much as it is able to) and this could cause it to overboost dramatically. I've had an intake hose come off the manifold because I overboosted.

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