A field guide to the sounds your car makes — squealing, knocking, grinding, hissing and more — with likely causes, how urgent each one is, and what to do next. When you're ready to pinpoint yours, record it and let AutoNoise AI analyze it for you.
High-pitched screech, usually when braking or when the engine is cold.
What to do
Inspect brake pads and belt within 1–2 weeks. If squeal turns into a grind, stop driving and book service.
Rhythmic metallic knock or ping from the engine bay, often under load or acceleration.
What to do
Reduce load and get a diagnosis quickly. Continued driving with rod knock can destroy the engine.
Metallic knock or ping that follows engine RPM? Read the engine knocking noise guide.
Metal-on-metal grind when braking, turning, or shifting gears.
What to do
Stop driving as soon as safely possible. Grinding almost always means a part has already failed.
Humming or growling that rises with speed? Read the wheel bearing noise guide.
Steady hiss from the engine bay, especially after shutting the engine off.
What to do
Check coolant level cold and look for steam. Vacuum leaks trigger rough idle and should be fixed to avoid drivability issues.
Single or repeated clunk over bumps, when braking hard, or shifting into gear.
What to do
Have suspension components inspected. Ball-joint or tie-rod failure is a safety issue — don't delay.
Rising-pitch whine that follows engine or wheel speed.
What to do
Top up fluids, then get a proper diagnosis. Gear whine that grows over weeks usually means an expensive rebuild ahead.
Humming or growling that rises with speed? Read the wheel bearing noise guide.
Rapid tick from the top of the engine, often louder when cold.
What to do
Check oil first. If the tick persists after a fresh oil change, book a diagnostic before it turns into a knock.
Metallic knock or ping that follows engine RPM? Read the engine knocking noise guide.
Loose, tinny rattle that comes and goes with RPM or road surface.
What to do
Rule out interior sources first. An exhaust or timing rattle should be inspected within a few weeks.
Most brake squeal comes from the wear-indicator tab on the brake pad rubbing the rotor to warn you the pads are near the end of their life. Glazed pads or a light rust film on cold rotors can also cause a temporary squeal that goes away after a few stops.
Deep, rhythmic knocking that follows engine RPM is almost always serious — usually detonation or a worn bottom-end bearing. A light tick or pinging under acceleration can be caused by low-octane fuel or carbon buildup and is less urgent, but still worth diagnosing.
No. Grinding almost always means metal is contacting metal — worn-through brake pads, a failed wheel bearing, or a damaged CV joint. Continuing to drive turns a moderate repair into a much larger one and can be unsafe.
A hiss usually points to a pressure or vacuum leak: coolant dripping onto hot exhaust, a cracked vacuum hose, or an exhaust leak near the manifold. Check coolant level and look for steam before driving further.
AutoNoise AI analyzes the recording plus the affected area of the car to suggest the most likely causes, a severity level and an estimated repair cost. It's designed to help you arrive at the mechanic informed — not to replace a hands-on inspection.
Record 10 seconds of the noise, mark the area of the car, and get likely causes, severity and estimated repair cost in under a minute.
Start a free diagnosis