Immobilizer or battery problem??

[S4PJH]

Hi all,

After leaving work today my car started to play up. After turning the ignition key the engine would start for about 2 seconds then cut out. The immobilizer light on the dash flashed a bit pointing to an immobilizer fault. After I tried it 3 times it started and ran fine. I got home and plugged Vag-com onto it and got the following fault code:

17978 - Engine Start Blocked by Immobilizer
P1540 - 36-11 - - - Intermittent

I checked the state of the battery and it was about 11.9 Volts so it needs replacing. Would a duff battery cause a fault like the above???