Cars usually warn you before something actually breaks — a sound changes weeks before a part fails completely. Knowing roughly what you're hearing means you walk into a garage sounding like you know what's going on, instead of just saying "it's making a noise."
When braking at the pedal
The most common noises drivers ever hear, and usually the cheapest to fix if caught early.
High-pitched squeal when you brake Book soon
Likely cause: Brake pads are wearing down. Many pads have a small metal tab built in specifically to make this noise as an early warning.
What to do: Get the pads checked — replacing them now is routine and inexpensive. Ignore it and it becomes the next one.
Grinding, metal-on-metal sound when you brake Get it checked now
Likely cause: Pads have worn through completely — metal is now grinding directly on the brake disc.
What to do: This damages the discs the longer it continues, turning a cheap pad swap into a much bigger bill. Get it looked at as soon as you can.
Steering wheel shakes or judders when braking Book soon
Likely cause: Often warped brake discs, sometimes from heat build-up on long descents.
What to do: Not usually an emergency, but book a brake inspection — it tends to get worse, not better, on its own.
Light squeal first thing in the morning, then stops Usually harmless
Likely cause: A thin layer of surface rust builds up on the discs overnight, especially after rain — completely normal, not the same as worn pads.
What to do: It should clear after your first few brake applications. If it doesn't stop once you're moving, treat it as one of the other braking noises above instead.
From the wheels or when turning steering & suspension
Grinding when turning tightly at low speed Get it checked now
Likely cause: A worn CV joint, which connects the wheels to the drivetrain.
What to do: Don't put this one off — a failed CV joint can affect your ability to drive the car at all.
Humming or rumbling that gets louder with speed Book soon
Likely cause: A wearing wheel bearing — often more noticeable on a gentle curve, sometimes changes pitch depending on which way you turn.
What to do: Get it checked before it progresses — a bearing that fails completely can affect steering control.
Clunking or rattling over bumps and speed humps Book soon
Likely cause: Usually a worn suspension component (like an anti-roll bar link) or a loose exhaust mount.
What to do: Not usually urgent on its own, but worth a look — it's a good early sign before something more expensive wears out.
Rhythmic slapping sound while driving Check now
Likely cause: Usually a flat or badly under-inflated tyre.
What to do: Pull over safely and check that tyre — driving on it further can damage the wheel itself.
From the engine bay under the bonnet
High-pitched squeal when accelerating Book soon
Likely cause: A worn or slipping accessory (drive) belt, the one that powers things like the alternator and power steering pump.
What to do: If it snaps while driving, you could lose power steering or charging — get it checked before that happens, not after.
Knocking or pinging from the engine Get it checked now
Likely cause: Could be several things, none of them minor — sometimes fuel-related, sometimes low oil, sometimes more serious internal wear.
What to do: Don't keep driving on this one hoping it goes away — a proper diagnosis now is far cheaper than the engine damage that follows if you ignore it.
Hissing or whistling from the engine bay Book soon
Likely cause: Often a vacuum leak or a worn hose losing pressure somewhere.
What to do: Can affect how the engine runs over time — worth booking in rather than ignoring.
Grinding when you turn the steering wheel Book soon
Likely cause: On cars with hydraulic power steering, this often means the power steering fluid is low.
What to do: Check the fluid level (see Fluids & Symbols) — if it's low, that suggests a leak worth getting checked too.
Not a noise — a feeling
Symptom guidance draws on RAC and AA published advice on common vehicle noises. These are general starting points, not a diagnosis — the same sound can have more than one cause depending on the car, so treat this as "what to mention to your mechanic," not a confirmed fault.