jerky steering when cold S40 2.4

[stevo12]

stevo12
hello can anyone help me with a steering problem on my volvo S40se 2.4. when the vehicle is cold or for 3 miles the steering is jerky and sticking, then releases and able to be turned, as i approach a bend the steering sticks then jerks free, i have been informed this could be a wet or damp sensor on the power steering unit? is this possible? how do i go about fixing this very dangerous fault that has occured, there is no warning light on the dash about the problem. thanks , stevo12