A shaking car needs different checks depending on whether the vibration occurs at idle, under acceleration, while braking or at a particular road speed. The pattern helps a technician; it does not establish a diagnosis.
Describe when it happens
At idle, note engine smoothness and warning lights. During acceleration, note whether it follows engine speed or vehicle speed. Under braking, describe pedal or steering-wheel vibration. At a steady road speed, note whether it is felt in the wheel, seat or whole body. Do not deliberately reproduce severe shaking on the road.
Useful checks while parked
From a safe position, look for a visibly flat or damaged tyre and check cold pressures against the vehicle placard. Note recent tyre fitting, a pothole impact or repairs. Do not crawl underneath an unsupported car or reach near a running engine.
Decide whether to stop
Strong or sudden vibration, poor steering or braking, a damaged tyre, smoke or a flashing engine warning calls for stopping safely and requesting help. For a mild persistent symptom, arrange an inspection before it worsens. Replacing parts from a symptom list can miss the real fault.
