Power steering assist problem

[Tarpo]

Could any one help me please I have a Ford Focus st2 when I come to start my car I turn the key and it comes up power assist steering and just makes a humming sound.I have changed the battery and the car ran for a couple of days but then it did it again after turning the key a few times it starts the car but then goes in limp mode so I turn the the key off and on again and ten it starts I’m at a loss at the moment regards Ian

[Luke4efc]

Have you done any of the basic checks?

What fault code are you getting?

Have you checked the battery voltage when the car won't start? Made sure the alternator is charging the battery sufficiently?

[Tarpo]

Yes it’s a new battery and when running the voltage is 14 volts the alternator is only 2 years old the car starts after about 3 turns then runs ok the problem only comes in when I leave for a while and just comes up power assist problem then after so many turn of the key it starts