Car trouble · Engine & check-engine light

My engine idles rough or shakes

The car shakes, stumbles or runs unevenly while stopped. A misfire or an air leak are the usual reasons.

Get to it this week

A starting point, not a diagnosis. Most parts stores read check-engine codes and test batteries for free.

Likely causes — tick the parts you want

Worn spark plugs
most likely · Doable with tools and a free afternoon
How to check: Check your records or the owner’s manual for when the plugs are due. Old plugs cause a shaky idle, especially when the engine is cold.
- Spark plugs (set)(Ask the counter to read the check-engine code for free — most parts stores will.)
- Spark plug socket
A failing ignition coil
possible · Doable with tools and a free afternoon
How to check: If the check-engine light is on, have the code read. A misfire code naming one cylinder often points to that cylinder’s coil.
- Ignition coil
A cracked vacuum hose
possible · Doable with tools and a free afternoon
How to check: With the engine running, listen under the hood for a hissing sound and look for cracked or loose rubber hoses near the top of the engine.
- Vacuum hose(Bring the old piece if you can, so the counter can match the size.)
A dirty throttle body
less likely · Most people can do this
How to check: Take the air intake tube off the throttle body and look inside. A thick black ring of buildup around the opening can cause a low, uneven idle.
- Throttle body cleaner

Your car — the counter needs this

YearMakeModelEngine (optional)

VIN (optional, most exact)Which parts store (optional)

If the counter doesn’t have a part, your shopper asks them to order it under your name and messages you the order number. When it comes in, send someone to collect it.

Not quite it?

My check engine light is flashing My check engine light is on My oil light is on My car hesitates when I accelerate I smell burning oil My car is getting worse gas mileage