The steering wheel is stiff to one direction when the engine is cold.
Possible of Cause of Stiff Steering Wheel in One Direction if the Engine is cold
Control Valve Assembly of Rack and Pinion is FaultyThis problem happens to a car with a power rack and pinion steering system. If this kind of problem is encountered the most common cause is a faulty control valve assembly of the rack and pinion steering. The control valve assembly is a device that directs pressurized power steering fluid when the driver turns the steering wheel to either left or right.
The control valve works by applying left pressure when the driver turns the steering wheel to the left and apply right pressure when the driver turns the steering wheel to the right making turning of the steering wheel easier for the driver.
Since the steering wheel is stiff when the engine is cold therefore the most obvious problem is the control valve assembly because when the engine is cold the control valve assembly is sticking then as the engine warms up the control valve is loosen up making the steering wheel also loosen up.
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Bring the car to a reputable shop then ask the mechanic to check the control valve just replace the control valve assembly to fix the problem. However it is also possible that the whole rack and pinion is needed to be replaced as well and it will cost you a lot, just hope that you will find a shop that will just replace the control valve.