2018 Kia Soul EV Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2018 Kia Soul EV and How to Restore Smooth Performance

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Reviewed by
Aisha
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 2018 Kia Soul EV 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 2018 Kia Soul EV 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.

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.

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 potential causes and diagnostic steps for a rough idle in a 2018 Kia Soul EV?

When dealing with a rough idle in your 2018 Kia Soul EV, it's essential to adopt a systematic diagnostic approach that prioritizes simpler fixes before delving into more complex problems. Start by checking the air filter; a dirty or clogged filter can significantly restrict airflow, leading to an unstable idle. If the air filter appears clean, inspect the spark plugs for any signs of wear or damage, as faulty spark plugs can cause misfiring and contribute to rough idling. Next, utilize an OBD-II scanner to check for any error codes that might indicate specific issues within the engine. If no codes are present, investigate potential vacuum leaks, which can disrupt the air-fuel mixture; a smoke test can be particularly effective in identifying these leaks. Following this, examine the fuel system, including the fuel filter and injectors, for any blockages that could affect performance. Additionally, test the mass airflow sensor to ensure it is functioning correctly, as improper readings can lead to idle instability. Finally, assess the ignition system components, such as the ignition coil, to confirm they are operating as intended. By following this structured approach, you can effectively diagnose and address the causes of a rough idle in your vehicle.

What are the common problems that could cause a rough idle in a 2018 Kia Soul EV?

When diagnosing a rough idle in your 2018 Kia Soul EV, it's essential to consider several common problems that could be affecting your vehicle's performance. One of the primary culprits is a dirty or clogged air filter, which can significantly restrict airflow to the engine, leading to an uneven idle. Additionally, faulty spark plugs may cause misfiring, contributing to the roughness you experience. Another potential issue is vacuum leaks, which can disrupt the delicate air-fuel mixture necessary for smooth engine operation. Fuel system problems, such as clogged fuel filters or injectors, can also hinder performance and result in a rough idle. Lastly, a malfunctioning oxygen sensor can throw off the air-fuel ratio, exacerbating idle issues. By regularly maintaining these components and addressing any signs of wear or damage, you can help ensure a smoother driving experience in your Kia Soul EV.

How urgent is it to address the rough idle in my 2018 Kia Soul EV?

Addressing a rough idle in your 2018 Kia Soul EV is crucial for maintaining the vehicle's performance and longevity. Ignoring this symptom can lead to more severe engine problems, decreased fuel efficiency, and ultimately, costly repairs. A rough idle often signals underlying issues that, if left unaddressed, may escalate into significant damage, compromising not only the vehicle's reliability but also your safety on the road. Regular maintenance and prompt repairs are essential to prevent these complications, ensuring that your Kia Soul EV operates smoothly and efficiently. Therefore, it is advisable to consult a professional mechanic at the first sign of a rough idle to diagnose and resolve the issue, safeguarding your investment and enhancing your driving experience.

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2018 Kia Soul EV Rough Idle: Causes & Repair Estimates