This tool provides general guidance — not professional mechanical advice. Always have a qualified mechanic inspect your vehicle before making any repair decisions.
#1 Most Likely
Car shakes while idling at stoplight
Typical Cost
$150 – $1,200
Engine mount replacement typically costs $200–$600 per mount per industry repair data (2024). Spark plug and ignition coil replacement may cost $200–$500. Vacuum leak repair varies widely by source. Urgency reflects worst-case cause (engine mount failure). Prices vary by vehicle make and region.
Wide range because the exact repair depends on what's causing the symptom.
- Worn or broken engine mounts
- Cylinder misfire from worn spark plugs or failing coil
- Significant vacuum leak
- Broken or worn transmission mount
A vehicle that shakes or vibrates noticeably while stopped at a light may indicate worn or failed engine mounts, a misfiring cylinder, or a significant vacuum leak. In the worst case, broken engine mounts allow the engine to move excessively, which can damage surrounding components and driveline parts.
What a mechanic will check
A mechanic will likely inspect engine mounts for cracks or complete failure, retrieve engine fault codes for misfires, and check vacuum hoses for leaks. Transmission mounts and flex disc joints may also be inspected if the shake is most prominent in Park.
What to say to your mechanic
“My car shakes quite a bit when I am sitting at a stoplight, but it seems better when I am moving. Can you inspect my engine mounts and check for misfires to tell me what may be causing the idle shake? I want to understand what may need to be addressed before we discuss repairs.”
Script based on industry repair procedures