Possible boost leak

[Zedhed]

Got a bit of a whistle when giving it some beans.sounds like a possible boost leak to me but could be wrong.would this have possibly triggered the trans failsafe message the other night.

[Horizon]

[quote="Zedhed"]
Got a bit of a whistle when giving it some beans.sounds like a possible boost leak to me but could be wrong.would this have possibly triggered the trans failsafe message the other night.
[/quote]
Turbo whistle is normal for the E53, I liked it, my X3 has the same engine but I don't get the whistle, possibly muffled out by the DPF.
Transfailsafe can be brought on by a failing battery/ low voltage. Keep the battery topped up with a charger/ conditioner if it's not frequently driven , or does short journeys.  Heck the voltage is over 12 volts
Or it could be a transmission problem,  It try the battery first.

[Zedhed]

Did a test on the battery and alternator already and checked out fine.alternator is kicking out 14v plus.

[X5Sport]

What can sometimes upset these cars is quick turning of the key to start.  I was led to believe that (depending upon options) there are dozens of little systems that all have to play nicely in the data buses and sometimes they have a slow day!  I was advised to turn, pause for the warning lights to cycle, then crank.  I used to get spurious - and scary warnings - regularly until I started doing that.  Very few after adopting this approach. 

A voltage drop is the usual cause the 'Transmission Failsafe' warning.  Two modules not playing nicely!

[Zedhed]

It came on the display the other night on the way home,but next morning it was fine,and nothing else since.