Q: Knocking noise underneath car.

asked by on

When driving my car, I hear a knocking noise coming from underneath, usually worse at slower speeds (45mph or lower). When I accelerate, the noise dissipates but will return when I'm coasting or on the brake. It makes this noise when I'm going straight and when I'm making left hand turns, but not as much when I'm turning right. It sounded like it could be a tire problem with the windows down (although I was told its something to do with the axel), and it comes from the front drivers side of the car. It also makes the steering wheel shake a little bit.

My car has 100000 miles.
My car has an automatic transmission.

Hi, thanks for writing in. Diagnosing the exact source of a vibration or noise is typically only possible through an onsite inspection. However, after reading the symptoms you’re describing, the two possible suspects may include the wheel bearings or the CV joints. Both components can cause steering wheel vibration at speeds and can also cause knocking sounds as the wheels turn. Here at YourMechanic, we can have a technician come to your home or office to inspect and diagnose this noise issue for you, and make or suggest the necessary repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Knocking noise underneath car.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: 2004 Mazda 6s (V6-3.0L Automatic) VS. 2004 Hyundai Elantra GLS

From your tax dollars, and the National Highway Transportation Safety Administration, the 2004 Mazda 6 has 0 Recalls and 0 Technical Service Bulletins - which all manufacturers are required to report for serious problems. The 2004 Hyundai Elantra has 5...

Q: Serpentine belt

There are a number of things that may cause this to happen. If the belt is not adjusted properly, this may put additional stress on it causing it to snap. If the AC compressor is beginning to fail, this will...

Q: Why can't i fix O2 sensor problem

In many circumstances, the O2 sensors are not the only culprit of a lean fuel curve. In many cases, a clogged fuel injector nozzle can also trigger the most common OBD-II error code (P-2191) that indicates a lean condition exists....

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...