2006 X5 Diesel intermittent cold start problem

[opienor]

Thanks powers1!

The problem gradually intensifies as outside temperatures drop. Lower temps equal more start attempts. Worst case happended at -4 deg. Fahrenheit when the engine just wouldn´t start at all and the car had to be towed. I´d say the problem appears between approx. -4 to 23 degrees F.
I think you may be right about this being some sort of a sensor or electronics related problem. Especially since I can clearly hear that the fuel pump fails to activate the times the car doesn´t start. Something appears to be wrong in the startup sequence. I glow, fail to hear the pump, crank with no start. This is repeated a number of times until the pump (I assume) suddenly comes to life when ignition is activated, the glow light goes out and voila the engine starts. I have tried to go from off to ignition without cranking a number of times to see if the pump suddenly starts, but without any luck. The cranking (without start) somehow seems to "wake up" the pump for the next start attempt.
The glow indicator lights up and then goes out before I start cranking. Everything appears normal in that department. And no error codes I´m afraid.