While driving your car sometimes your car steering wheel becomes stiff for the moment.
Car Problem Diagnosis
This kind of problem often cause by a faulty steering pump, as you may not aware of, power steering system makes your car easier to steer during driving, this includes component such as power steering pump which pumps power steering fluid to create hydraulic force applied to the steering gear thus making your car easier to steer.
When your power steering pump occasionally fail, such as when the pump stops pumping for a moment this will make your car steering wheel become stiff momentarily.
Also, if the power steering belt becomes wet it can slip thus making your car steering wheel become stiff.
Possible Cause of Stiff Steering Wheel
Faulty power steering pump
How to fix Stiff Steering Wheel
The only solution for this kind of problem is to replaced the power steering pump, bring your car to a reputable auto repair shop and have a mechanic to confirm whether the problem lies with your car power steering pump. Also have the mechanic inspect your power steering system explain your diagnosis of the problem.