In the core rules book, it says (main book, page 72) when Walkers fire their weapons, they pivot to face their target and their weapons have a 45 degree arc of LOS.
In the Chaos Space Marines FAQ (V1.1), it's stated, when working out which targets are visible for the Fire Frenzy, that the Chaos Dreadnought's LOS is limited to 45 degrees from its weapons.
Having to pivot to fire on a target, and the clairification on the Chaos Dreadnought, implies that a Walker's LOS is limited to 45 degrees on it's front. Turning to keep an undesirable enemy out of a 45 degree LOS would allow better control of the Penitent Engine in exchange for a higher likely hood of exposing it's weaker backside to enemy fire. So it wouldn't be without risk, but I cannot find anything that explicitly says that walkers LOS is limited to 45 degrees...or that it's a full 360 degrees for that matter.
So my rules questions is: Is the LOS for Rage suffered by a Sisters of Battle Pentient Engine limited to a 45 degree front view of the Penitent Engine, or a full 360 degrees?