2018 Jeep Grand Cherokee Has Rough Idle

Common Causes of Rough Idling in Your 2018 Jeep Grand Cherokee and How to Resolve Them

Find Repair Location
Reviewed by
Bo Fader
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 Jeep Grand Cherokee 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 Jeep Grand Cherokee 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 initial diagnostic steps to take for a rough idle in a 2018 Jeep Grand Cherokee?

When faced with a rough idle in your 2018 Jeep Grand Cherokee, it's essential to adopt a systematic diagnostic approach to identify and resolve the issue effectively. Start by checking for fault codes using an OBD-II scanner, as these codes can reveal specific problems within the engine's systems. Next, inspect the spark plugs for wear or fouling, as these components play a crucial role in engine performance. A clean air filter is also vital; ensure it is free from dirt and debris to maintain proper airflow. Additionally, examine the vacuum hoses for any signs of damage or disconnection, as leaks can significantly impact engine operation. Don't overlook the throttle body; cleaning it of carbon buildup can enhance idle quality. Finally, test the mass airflow sensor to ensure it is functioning correctly, as a faulty sensor can disrupt the air/fuel mixture. By following these steps in order, you can effectively diagnose and address the rough idle issue, ensuring your Jeep runs smoothly.

What are the common problems that could cause a rough idle in a 2018 Jeep Grand Cherokee?

When dealing with a rough idle in your 2018 Jeep Grand Cherokee, it's essential to understand the common problems that could be at play. One of the first areas to check is the air filter; a dirty or clogged filter can significantly restrict airflow to the engine, leading to performance issues. Additionally, inspect the spark plugs, as worn or faulty plugs can cause misfiring, which directly contributes to a rough idle. Another critical component to examine is the vacuum system for any leaks, as these can disrupt the air-fuel mixture necessary for smooth engine operation. Fuel system issues, such as a clogged fuel filter or malfunctioning fuel injectors, can also impact engine performance and should not be overlooked. Furthermore, the mass airflow sensor plays a vital role in regulating the engine's air intake; if it's malfunctioning, it can lead to an improper air-fuel mixture. Lastly, consider the EGR valve, as a faulty valve can disrupt the combustion process, resulting in rough idling. By addressing these common issues through regular maintenance and timely repairs, you can effectively resolve the rough idle problem and enhance your vehicle's performance.

How urgent is it to address the rough idle in a 2018 Jeep Grand Cherokee?

Addressing a rough idle in your 2018 Jeep Grand Cherokee is not just a matter of comfort; it is crucial for the vehicle's overall health and performance. A rough idle can indicate underlying engine problems, such as issues with the fuel or ignition systems, which, if left unattended, may escalate into more severe complications. Ignoring this symptom can lead to decreased fuel efficiency and poor engine performance, ultimately resulting in costly repairs down the line. Moreover, a rough idle could signal serious issues that may worsen over time, potentially compromising your vehicle's safety and reliability. Regular maintenance and prompt repairs are essential to prevent further damage and ensure your Jeep operates smoothly. Therefore, if you notice a rough idle, it is imperative to address it as soon as possible to maintain the longevity and efficiency of your vehicle.

You’ve got options with RepairPal

Whether you need a more accurate auto repair estimate or help finding a reputable shop in your area, we’ve got you covered.

2018 Jeep Grand Cherokee Rough Idle: Causes & Repairs