Symptom
A noise that was not there before — knocking, whining, ticking or rumbling. Worth describing precisely, since the character and whether it varies with engine speed or road speed narrows the cause enormously.
Also described as: strange noise, knocking noise, engine noise, tapping, ticking, whining, rumbling, clattering, صدای غیرعادی از موتور, صدای عجیب موتور, ruido raro motor, motor ruido extraño, sonido extraño motor, صوت غريب من المكينة, صوت مزعج من الموتور, صوت غريب من المحرك, أصوات غير طبيعية بالمكينة, صوت مش طبيعي
46 of the 207 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
Worth describing precisely, since the character and whether it varies with engine speed or road speed narrows the cause enormously. This entry is the parent of the more specific ones in this group, and its job is to route the reader to them.
Start with what the noise follows, because it costs nothing and separates whole systems. Engine speed — it changes when you rev in neutral. Road speed — it stays the same through a gear change and disappears as the car coasts to a stop. Load — it appears under throttle and vanishes when you lift.
Then the character, because each has its own family:
Locate it before diagnosing. A length of hose held to the ear, or a mechanic's stethoscope, distinguishes an ancillary bearing from something inside the engine in a minute — and removing the auxiliary belt for a brief run separates everything it drives from everything it does not, which is the single most productive test on this page.
A deep knock that grows with load is a stop-driving matter. Bottom-end noise gets worse quickly and the failure is sudden.
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Changes with engine speed when revved in neutral | The engine or something it drives — not wheels, tyres or driveline | Rev in neutral and listen. This one test removes the entire road-speed population. | Pursue by character: tick, knock, whine or rattle each have their own entry in this vocabulary. |
| Stops when the auxiliary belt is removed for a brief run | A driven ancillary — alternator, water pump, power steering pump, air conditioning compressor or a tensioner | Run briefly with the belt off, watching engine temperature. This is the most productive single test here. | Renew the noisy ancillary. Spin each by hand with the belt off to identify which. |
| Deep knock that follows engine speed and worsens under load | Bottom-end bearing wear — the serious one | Stop rather than investigate at length. Check oil pressure and level; a knock with low pressure is conclusive enough to stop. | Recover the vehicle. This fails suddenly and continuing turns a rebuild into a replacement engine. |
| Follows road speed, unchanged through gear changes | Wheels, tyres, bearings or driveline rather than the engine | Hold a road speed in two different gears. No change means road speed. | Pursue as a driveline or wheel-end noise — see the droning entry in this group. |
| Only under load, gone on lift-off | Pressure or combustion — a boost leak, or pinking under load | Distinguish a hiss from a metallic rattle: the first is air escaping, the second is combustion. | Diagnose as the relevant entry — hissing under acceleration, or pinking under load. |
| Cannot be located by ear | Not yet a diagnosis — location comes before cause | Use a stethoscope or a length of hose at each ancillary and along the block. A minute of listening beats an hour of guessing. | Locate first. Parts fitted on a described noise rather than a located one are usually the wrong parts. |
Changes with engine speed when revved in neutral
Stops when the auxiliary belt is removed for a brief run
Deep knock that follows engine speed and worsens under load
Follows road speed, unchanged through gear changes
Only under load, gone on lift-off
Cannot be located by ear
Listed with the codes that most typically present this way first — the likeliest place to start.
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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