Why Is My Car Juddering?

Driving on the road car accelerating

There’s nothing more unsettling than a new noise emanating from your car, whether it’s accompanied by a warning light or not. A consistent juddering, jerking or sputtering movement or noise can be particularly alarming, as it can indicate a significant risk to you and your passengers, so it’s vital to diagnose the issue as soon as possible.

There are plenty of possible causes, but to help you get to the bottom of the problem quickly, we’ve put together a list of the most common reasons your vehicle might develop a juddering movement.

Faulty Spark Plugs

If your spark plugs are worn-out, or need a good clean, they can cause the engine to misfire, which makes your car jerk or judder when you accelerate. This is generally a fairly cheap fix, even if you don’t have the know-how to replace them yourself. Once you’re certain this is the issue, you can find the right spark plugs for your vehicle using our fast finder tool, and take them to your local garage to be fitted.

Failing Ignition Coil

The ignition coils in your vehicle amplifies the power from the battery, which creates enough electricity for the engine to fire. If one of your ignition coils isn’t working, one of your cylinders will fail to operate, which could cause the engine to make a juddering noise. A faulty ignition coil could also cause symptoms such as poor fuel economy, or problems starting your car – so if the juddering persists, don’t put off having it checked out. 

Broken Lambda Sensor

Most modern cars have at least one lambda sensor in the exhaust system. This sensor ensures that your fuel has the right ratio of oxygen to petrol or diesel, so your car can adjust it accordingly. If this sensor is malfunctioning, then it might give your car’s computer an incorrect reading, so the fuel mixture is changed, and the proportion of air in it becomes too large. This would cause your car to issue a juddering noise, and could result in engine damage.

Lambda sensor oxygen sensor

Faulty CV Joints

CV joints (or constant velocity joints) are another common cause of a juddering motion in your car. If they’re faulty, they can prevent the drivetrain from transmitting sufficient power, and your car might pull to one side, start to judder or emit a loud clicking noise when you’re turning. Don’t ignore a broken CV joint – it could cause your car to grind to a halt on the road if left unattended. 

Juddering Brakes

If your car only judders when you apply the brakes, there could be several culprits, but it’s most likely a problem with your brake discs or pads. Here are the key things to check for:

  • An incorrectly fitted brake disc causing misalignment
  • A brake pad that’s become worn down and ineffective
  • A brake disc overheating, and becoming distorted as a result
  • A brake disc which is thicker on one side, due to uneven wear

Any of these issues could cause a disconcerting juddering noise when you brake, and compromise your safety on the road. If you suspect this is the case, or your brake pad warning light has come on, get yourself to the garage.

Juddering During Acceleration

A juddering noise while you accelerate could indicate a couple of potential problems. It may be your spark plugs, as we mentioned earlier, but it could also be a result of a clogged catalytic converter, causing a blockage that would stop the exhaust systems airflow working smoothly. If this is the case – you might also notice a sulfuric smell when you accelerate. Some minor blockages can be cleared with a good catalytic converter cleaner, but if you’re not sure how to approach it, take it to a mechanic.

It’s important to note that you may not be able to establish which problem is causing your car to judder safely at home, so taking it to your local garage is usually your best option.

For more helpful diagnostic advice, information on the industry and product recommendations, take a look at our other recent blogs.