2021 Kia Sorento Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2021 Kia Sorento and How to Resolve Them

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Reviewed by
Andrew Hajjar
Written by RepairPal Car Genius
Updated January 14, 2025
0%
21% chance it's the
Spark Plugs
0%
15% chance it's the
Ignition Coil
0%
64% chance it's
Something else
The most common reasons a 2021 Kia Sorento has rough idle are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
  • Spark Plugs: Worn or fouled spark plugs can lead to misfires, poor fuel economy, and difficulty starting the engine.
  • Ignition Coil: A faulty ignition coil can cause misfires, rough idling, and difficulty starting the engine due to inadequate spark delivery to the spark plugs.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2021 Kia Sorento has rough idle?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

Brake caliper failure occurs in two different ways, and they create different symptoms.

The caliper can become stuck, in which case it won't release the brake pads. The seized caliper will cause the vehicle to brake constantly on one side, forcing the car to move toward that side. This pulling will be accompanied by a strong odor from one wheel.

Another way calipers fail is by leaking. If the caliper leaks, the brake pedal will feel too easy to push, and will sink all the way to the floor when held. Braking will become less effective the longer this goes on. There may also be brake fluid leaking onto the wheel.

Here are a few common symptoms of worn-out brake pads:

  1. Low brake pad warning light is on: Not all vehicles are equipped with this system, but if yours is, this dashboard indicator light will likely be the first signal it’s time to replace your brake pads.
  2. Brakes start to squeal regularly: This is often one of the first signs of worn brake pads and is caused by a metallic piece built into brake pads for this exact purpose. This part contacts the brake rotor to make a squealing or whining noise when the pads are low.
  3. Brakes make loud grinding noise: If not addressed early enough, your brake pads may get so worn that the metal backing plate of the pad grinds against the metal rotor.
  4. Brake pads look thin: You may be able to visually check your brake pad thickness to determine if they need replacement.

Brake rotors are mainly maintenance free, but when they have been subjected to abnormally hard use, the heat they absorb can cause the metal to turn blue, and cracking to occur. When this occurs, customers often specify they have lost braking power, or the vehicle's brakes are making noise. There may be no symptoms at all related to changing the brake rotors, since it is recommended to change brake rotors on most modern vehicles when performing a standard brake service.

Most often, a brake system inspection will just be a routine portion of manufacturer specified maintenance, and will be performed at mileage intervals. In those cases, there will likely be no symptoms. However, when a brake system makes a funny noise, causes vibration, is hard to use, will not slow the vehicle, prevents the vehicle from driving, makes the vehicle pull to one side, or leaks brake fluid, the vehicle will need a visit dedicated to the inspection of the brake system.

What are the steps to diagnose a rough idle in a 2021 Kia Sorento?

To effectively diagnose a rough idle in a 2021 Kia Sorento, it’s essential to adopt a systematic diagnostic approach that begins with simpler checks before progressing to more complex issues. Start by utilizing an OBD-II scanner to retrieve any error codes from the vehicle's computer system, as these codes can provide immediate insights into potential problems. Next, inspect the air filter; a dirty or clogged filter can severely restrict airflow, leading to performance issues. After that, examine the spark plugs for signs of wear or fouling, as they play a critical role in engine combustion. Once these initial checks are complete, focus on the fuel system, looking for clogs in the fuel filter or malfunctions in the fuel injectors that could impact engine performance. Additionally, inspect the vacuum hoses for any leaks or cracks, as these can disrupt the air-fuel mixture and contribute to a rough idle. Lastly, ensure the throttle body is clean and functioning properly, as dirt buildup or malfunctions can also lead to idle issues. By following this structured approach, you can effectively identify and address the underlying causes of a rough idle in your Kia Sorento.

What are the common problems that could cause a rough idle in a 2021 Kia Sorento?

When dealing with a rough idle in your 2021 Kia Sorento, it's essential to consider several common problems that could be affecting your vehicle's performance. One of the first areas to check is the air filter; a dirty or clogged air filter can significantly restrict airflow to the engine, leading to an uneven idle. Additionally, inspect the spark plugs, as worn or faulty plugs can cause misfiring, which directly impacts idle quality. Another critical component to examine is the vacuum system; any leaks can disrupt the air-fuel mixture, resulting in a rough idle. Fuel system issues, such as a clogged fuel filter or a malfunctioning fuel pump, can also hinder proper fuel delivery, contributing to idle problems. Furthermore, a faulty oxygen sensor may cause the engine to run either too rich or too lean, affecting its overall performance. Lastly, don’t overlook the throttle body; carbon buildup or a malfunctioning throttle position sensor can lead to irregular idling. By systematically checking these components, you can identify and address the root cause of the rough idle, ensuring your Kia Sorento runs smoothly.

How urgent is it to address the rough idle in a 2021 Kia Sorento?

Addressing a rough idle in your 2021 Kia Sorento is crucial for maintaining the vehicle's performance and longevity. Ignoring this symptom can lead to a cascade of problems, including decreased fuel efficiency and engine performance, which may escalate into more severe mechanical failures. A rough idle often indicates underlying issues, such as dirty fuel injectors or worn spark plugs, which can be relatively easy to fix with routine maintenance. However, it can also signal more serious concerns, like a malfunctioning sensor or a vacuum leak, that require immediate professional attention. By prioritizing the resolution of a rough idle, you not only enhance your driving experience but also safeguard against costly repairs down the line, ensuring your vehicle remains safe and reliable on the road.

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2021 Kia Sorento Rough Idle: Causes & Repair Costs