2007 Golf Plus 1.9tdi Fault codes

Hi all, My wife has a Golf plus and 95% of the time its fine.
Occasionally the ASR light comes on for a couple of miles and then goes off. Again the orange power steering light will do the same.
Iv'e noticed that this usually happens after the car has been standing for some time. Maybe voltage drop from partially discharged battery ?
I have read the fault codes an got:

00778 Steering angle sensor
000883 Ignition switch (D) term 5 sporadic 012 - elect fault
02195 Dimmer switch (E20) sporadic 009 open or short

I am wondering if the fault in the ASR and steering is caused by an intermittent loss of power from the ignition switch.
I guess the dimmer switch fault is something else entirely.

Wonder if anyone has any thoughts on this before I go changing parts.

Thanks in advance
Geoff