2020 Mercedes-Benz GLE450 Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2020 Mercedes-Benz GLE450 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 2020 Mercedes-Benz GLE450 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 2020 Mercedes-Benz GLE450 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 initial diagnostic steps to take for a rough idle in a 2020 Mercedes-Benz GLE450?

When addressing a rough idle in your 2020 Mercedes-Benz GLE450, it's essential to adopt a methodical diagnostic approach. Start by checking for fault codes using a diagnostic scanner, as these codes can reveal specific issues affecting engine performance. Next, inspect the spark plugs; ensuring they are clean and functioning properly is crucial, as worn plugs can lead to misfires and an unstable idle. Don’t overlook the air filter; a clogged filter can restrict airflow, exacerbating idle problems. Additionally, examine the vacuum lines for leaks, as any disruption in the air-fuel mixture can significantly impact engine performance. Assess the fuel system components, including the fuel filter and injectors, to ensure they are delivering fuel efficiently. Finally, take a look at the throttle body for any buildup that could hinder its operation. By following these steps, you can effectively identify and address the root causes of a rough idle, ensuring your vehicle runs smoothly.

What are the common problems that could cause a rough idle in a 2020 Mercedes-Benz GLE450?

When dealing with a rough idle in your 2020 Mercedes-Benz GLE450, it's crucial to understand the common problems that may be at play. One frequent culprit is a dirty or faulty mass airflow sensor, which can disrupt the delicate balance of air and fuel entering the engine, leading to an uneven idle. Additionally, vacuum leaks can introduce unmetered air into the system, further complicating the air-fuel mixture and causing instability in the engine's performance. Worn or faulty spark plugs are another common issue, as they can lead to misfires that manifest as a rough idle. A clogged fuel filter may also be to blame, as it restricts fuel flow, impacting engine performance at idle. Furthermore, the idle air control valve plays a critical role in maintaining the engine's idle speed; any malfunction here can result in erratic idling. Lastly, a faulty oxygen sensor can disrupt the air-fuel ratio, contributing to rough idling and other performance issues. By being aware of these potential problems, DIY enthusiasts can take proactive steps to diagnose and address rough idle issues, ensuring their GLE450 runs smoothly. Regular maintenance and timely repairs are key to preventing these issues and maintaining optimal vehicle performance.

How urgent is it to address the rough idle in my 2020 Mercedes-Benz GLE450?

Addressing a rough idle in your 2020 Mercedes-Benz GLE450 is not just a matter of comfort; it is crucial for the vehicle's overall performance and longevity. A rough idle can indicate serious underlying issues, such as problems with the engine, fuel system, or ignition components. If these symptoms are ignored, they can escalate into more severe problems, leading to decreased fuel efficiency and potential engine damage. Moreover, a rough idle can increase the risk of engine stalling, which poses safety hazards while driving. For DIY enthusiasts, it is essential to recognize that timely maintenance and repairs can save you from costly repairs in the future. By diagnosing and addressing the rough idle promptly, you can ensure that your GLE450 operates smoothly and efficiently, ultimately enhancing your driving experience and preserving the vehicle's value.

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