5 Common Causes of Car Shaking During Idling

While your car might shake while you’re driving at high speeds on a bumpy road, it tends to be calm when you’re stopping or staying idle. If you feel your steering wheel shake and vibrate while standing still, this can be a sign of various issues with the engine.

You’ll want to get to the bottom of this problem before it gets any worse and your fuel consumption increases or the engine is in need of repairs.  Take a look at some of the most common causes of idle car shaking.

1. Worn-out spark plugs

Spark plugs play an essential part in engine combustion. Once there’s a perfect mixture of air and fuel, the spark plug adds the necessary spark to ignite this combination in the cylinder. A worn-out spark plug that has been contaminated by oil or carbon deposits won’t be able to ignite the fuel, reducing the power created and creating rough idling.

It’s recommended that you replace spark plugs every 30 to 50 thousand miles to make sure this situation doesn’t happen. If you run into this issue early, you can simply replace the spark plugs whenever it’s necessary.


2. Faulty timing belts

Some of the most common causes of car shaking during idling involve issues with timing belts and their accessories. Components that are connected to a timing belt, such as fans, won’t move consistently if the belt is damaged. This causes fans to make strange noises and cause engine vibrations.

Open up the hood and inspect the belts from time to time. As long as they have no cracks or ribbing, there shouldn’t be issues when running the engine. If you notice that the belts aren’t fastened correctly, you can tighten them to resolve the problem.

3. Clogged air filters

As the name would suggest, air filters help filter the air that enters your engine. As your car moves and lets in the outside air, various dust and dirt particles make their way inside. The air filters make sure that these particles don’t disrupt the fuel mixture.

If the filters get clogged, the engine won’t receive the necessary air for combustion. The vehicle will start running rich, which increases fuel consumption and causes the car to shake while idling. As you might have guessed, the only thing you have to do in this situation is replace the air filter. Your car will then run smoothly and without issues.

4. Damaged motor mounts

The purpose of motor mounts is to keep the engine attached to the car it’s powering. If the car is idling and the motor mounts aren’t functional, nothing is stopping the engine from moving around.

How can you tell if the mounts are at fault for the car shaking? While the car is running, put it in neutral and see if the vibrations decrease. If they do, you can be reasonably sure it’s an issue with the motor mounts.


You shouldn’t try to take care of the problem on your own. It’s recommended that you find an experienced car mechanic to take a look at your engine. This way, you can confirm the source of the problem and have it fixed asap.

5. Dirty fuel injectors

While fuel passes through the injectors, it can leave small deposits of carbon, varnish, or other sediments that clog up the system. If the occasional fuel injector is blocked by these sediments, the engine won’t receive even amounts of fuel during the regular cycle. Since the flow to the combustion chamber is disrupted, the car will start shaking and shuttering from time to time.

To resolve the issue, you must clean the fuel injectors or replace them if the problem is extensive. A fuel injector cleaner will do the job if the sediment hasn’t clogged up the system completely. Otherwise, you’ll have to take the car to a mechanic.


In most cases, you should take your car to a mechanic if the car starts shaking while idle or at rest. If you have a little experience with fixing cars, you can try to diagnose the issue and replace faulty parts on your own. However, if it’s a serious problem, there’s no reason to delay repairs as they could cause further issues down the road. Pay a visit to your local mechanic so that you don’t have to worry about the car breaking down at an inopportune moment.