Symptoms
- Squeal occurs only when turning the steering wheel
- Louder at full lock (steering wheel turned all the way)
- May be worse when the engine is cold
- Steering may feel normal despite the noise
Likely causes
- CommonLow power steering fluidLow fluid makes the pump work harder and can cause noise, especially at full steering lock.
- CommonWorn or glazed serpentine belt slipping under steering loadThe added resistance from the power steering pump exposes belt wear.
- PossibleFailing power steering pumpA worn pump can whine or squeal under load even with proper fluid level.
- PossibleAir trapped in the power steering fluidAir bubbles can cause noise and reduce steering assist smoothness.
- PossibleWeak belt tensioner unable to handle steering pump loadThe tensioner may not maintain enough pressure specifically under steering load.
What to do
- Check the power steering fluid reservoir and top off to the proper level if low, using the fluid type specified in the owner's manual.
- Turn the wheel fully to one side and then the other with the engine running (safely, in park or neutral) to see if the noise correlates with steering effort.
- Inspect the serpentine belt for glazing or cracking, since it's often the actual source even when the noise seems tied to steering.
- Check under the car and around the power steering pump/reservoir for any signs of fluid leakage.
- If fluid is fine and belt looks good, the power steering pump itself may be wearing out internally.
- Bleed the power steering system per the owner's manual if air intrusion is suspected after a fluid top-off.
- Have a mechanic check belt tensioner strength and power steering pump condition together.
- Avoid running the power steering system low on fluid for long, since it can cause pump damage over time.
Tools and parts
- Flashlight
- Power steering fluid
- Funnel
Power steering fluidSearch: “power steering fluid for [year make model]”
Power steering pumpSearch: “power steering pump for [year make model]”
When to call a pro
If topping off fluid doesn't stop the squeal, have a mechanic check the belt, tensioner, and power steering pump.
Safety
Use caution
Keep hands and clothing clear of the belt and pulleys while the engine is running during diagnosis.