How To Diagnose A Failing Power Steering Pump

A power steering pump typically lasts the life of the car with proper maintenance. But sometimes it will fail sooner than expected. One of the most common causes of power steering pump failure is a bad bearing. It’s not unheard of for issues with the driving belt to cause power steering pump failure, as well.

Symptoms Of A Failing Power Steering Pump

Bad Subaru Power steering pump

When your steering starts to feel odd, then chances are your power steering pump is going bad. Power steering pump noise is usually an indicator, too. Here are some of the symptoms to look for:

  • Stiff steering at slow speeds.
  • Creaking, groaning, and/or whining sounds when turning.
  • A squealing noise when the engine is started.

Ruling Out Other Issues First

Sometimes the power steering pump is still in good shape, but is underperforming due to other issues. Before tinkering around with the power steering pump, let’s rule out three potential issues that could be affecting the pump’s performance:

  • A bad serpentine belt: The serpentine belt powering the pump could be in bad shape. When it’s cracked or loose, the pump isn’t getting as much power as it should. A power steering pump whine usually means that the serpentine belt is slipping. So if you hear a whine, then you definitely want to check out the belt first.
  • Contaminated power steering fluid: Power steering fluid is constantly heated up and it gets contaminated by dirt and debris over time. Steering fluid that’s too dirty will impact the pump’s performance.
  • Leaking power steering fluid: Power steering systems should not leak. Check the power steering fluid reservoir. If it is low, you have a leak that needs to be repaired.

It’s a good idea to inspect these items before checking your pump for any damage or contamination.

The Diagnostic Process

If the serpentine belt and the steering fluid look good, then the problem likely lies with the power steering pump. Grab a pressure gauge and then:

  1. Ensure that the shutoff valve is fully open.
  2. Check the reservoir to make sure it is full of clean power steering fluid.
  3. Connect the pressure gauge to the pump.
  4. Start the engine and then fully turn the steering wheel a few times to warm up the fluid and to release air bubbles.
  5. Leave the engine idling and close the shutoff valve for a couple of seconds (no more than 5 seconds!) while keeping an eye on the pressure gauge.
  6. Check your Subaru service manual for the appropriate pressure range. Your power steering pump should produce pressure that falls within Subaru’s guidelines. If it doesn't, then your power steering pump isn’t performing right and it may need to be replaced.

Finding The Right OEM Replacement Power Steering Pump For Your Subaru

New Subaru Power steering pump

Does your power steering pump needs to be replaced? The good news is that it’s really easy to find a genuine OEM replacement part. All you have to do is to visit a reputable online shop like Then perform a search on your Subaru to find the right power steering pump for your car.

Each Subaru has a certain power steering pump designed to fit into its steering system perfectly. For example, this OEM Subaru power steering pump is designed specifically for 2005-2009 Outback and Legacy models.

Please contact us if you need assistance finding the right OEM power steering pump for your car.