runs fine cold but rough when hot · rough running at operating temperature
The engine runs smoothly when cold but develops a rough idle, hesitation or misfire once it reaches normal operating temperature.
Note how long it takes (in minutes of driving) before the rough running starts - this helps a mechanic reproduce the fault during diagnosis.
Usually safe short-term, but get it looked at - heat-triggered faults tend to be intermittent and harder to diagnose the longer they are left.
Describe your situation more precisely (e.g. exactly when it gets worse, how long it lasts) and get an expanded, personalized breakdown.
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Descriptions are for guidance only and do not replace a workshop inspection. If you are ever unsure whether it is safe to keep driving, pull over in a safe spot.
Rough or shaky idle
WarningThe engine feels rough, shaky or uneven while sitting still (in park or at a stoplight), as opposed to running smoothly.
Engine stalls while driving or idling
SeriousThe engine unexpectedly shuts off entirely, either while idling (at a stop) or, more seriously, while actively driving.
Car vibrates or shakes at idle
WarningThe car shakes or vibrates noticeably while stationary with the engine running (in park or neutral), but smooths out once moving.
Squealing noise right after starting the engine
WarningA high-pitched squeal that happens right when the engine starts, especially on a cold morning, and often fades after a few seconds.
