2005 Nissan Altima Power Steering Failure?

After 60,000 miles, my steering wheel started to become difficult to turn like I’d lost power steering. The problem was intermittent and my fluid level didn’t appear to be low. After about a week I took my car to Nissan service to diagnose the problem and they came back with a 'replace the steering shaft knuckle" solution. I was expecting a bad pump or slipping belt.

I’m not very familiar with the all of the components that are involved and was looking for some help.

Is there a steering shaft knuckle for each tire? Does this diagnosis make sense? Is it possible that a simple fluid replacement could fix this problem?

The mechanic said that he pressure tested the lines and put some new fluid in the system during his troubleshooting. Because the part had to special ordered, I couldn’t get the repair done the same day and I drove it home. Oddly enough the problem was gone and has not re-appeared after three days.

Your vehicle has what is called Variable Assist Power Steering. This system uses a sensor in the steering column called the Hand Wheel Sensor and the Vehicle Speed Sensor. From the information from these sensors, the computer determines how much steering power assist is required. The computer then adjusts the pressure valve from the power steering pump to provide the steering power assist required for that condition.

If any of sensors is faulty, or if the pressure control valve is faulty, steering can be difficult at slow speeds.