Low tire pressure: Check and adjust tire pressures.

The wheels are out of alignment: Have the wheels aligned.

The power steering box or rack or power steering pump is bad: Repair or replace steering gear or pump as required.

The fluid level in the power steering reservoir is low: Fill fluid to proper level.

The power steering drive belt is damaged or broken: Replace power steering drive belt.

The steering gear needs to be lubricated or repaired: Lubricate or replace steering gear parts as required.