This is low on power with a great deal of white smoke.
Codes are:-
12 boost pressure sensor, present.
46 Injection adjust valve, present.
51 EGR position sensor, present.
The EGR valve was being driven hard open and the motor was incredibly hot. I closed the EGR by hand and left it disconnected. In this state the engine black smokes.(unless of course the valve is pressed to close, something for me to check)
When the fault occurred the tachometer stopped at the same time.
I would be suspicious of water ingress in the ECU connector or similar but getting the ECU out is many hours of work because it is in the A-pillar behind a security cover.
The loss of tacho made me think of lost rpm sensor signal in the pump but there are no codes relating to that.
Corroded filler neck and fuel pipes is a known problem causing pump contamination but why this would affect the tachometer is difficult to imagine.