2020 Mercedes-Benz C43 AMG Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2020 Mercedes-Benz C43 AMG and How to Resolve Them

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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 2020 Mercedes-Benz C43 AMG 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 C43 AMG 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 steps to diagnose a rough idle in a 2020 Mercedes-Benz C43 AMG?

To effectively diagnose a rough idle in your 2020 Mercedes-Benz C43 AMG, start with a systematic approach that prioritizes simpler checks before delving into more complex diagnostics. Begin by using an OBD-II scanner to check for any error codes, as these can provide immediate insights into potential issues. Next, inspect the spark plugs for wear or fouling, as these components are crucial for proper engine performance. A clean air filter is also essential, so ensure it is free from dirt and debris that could restrict airflow. Following this, examine the vacuum hoses for any cracks or disconnections, as leaks can significantly impact engine operation. Testing the mass airflow sensor is another critical step, as a malfunctioning sensor can lead to incorrect air-fuel mixtures. Don’t overlook the fuel system; check for clogged injectors or a failing fuel pump, as these can also contribute to a rough idle. Finally, inspect and clean the throttle body to ensure it is functioning correctly. By following this structured diagnostic approach, you can identify and resolve the underlying 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 C43 AMG?

When dealing with a rough idle in your 2020 Mercedes-Benz C43 AMG, it's crucial to understand the common problems that could be at play. One of the primary culprits is a dirty or faulty mass airflow sensor, which can disrupt the delicate balance of the air-fuel mixture, leading to an unstable idle. Additionally, vacuum leaks can create an improper air-fuel ratio, further exacerbating the issue. Worn or faulty spark plugs are another frequent cause, as they can lead to engine misfires that manifest as rough idling. Clogged fuel injectors may also hinder fuel delivery, impacting the engine's performance. Furthermore, issues within the ignition system, such as failing ignition coils, can contribute to this problem. A malfunctioning throttle body can disrupt air intake, while problems with the engine control module (ECM) can introduce software glitches or sensor malfunctions that affect idle quality. Addressing these issues promptly is essential for maintaining optimal vehicle performance and preventing further damage, so if you notice a rough idle, consider having your vehicle inspected by a qualified mechanic.

How urgent is it to address the rough idle in a 2020 Mercedes-Benz C43 AMG?

Addressing a rough idle in your 2020 Mercedes-Benz C43 AMG is not just a matter of comfort; it is crucial for the overall health of your vehicle. A rough idle can indicate underlying engine problems that, if ignored, may escalate into more severe issues, potentially leading to costly repairs. Additionally, a rough idle often correlates with decreased fuel efficiency, which can impact your wallet over time. By taking prompt action, you not only enhance your driving experience but also safeguard your engine from further damage. Regular maintenance and timely repairs are essential in preventing complications that could compromise your vehicle's performance and longevity. Therefore, if you notice a rough idle, it is advisable to investigate and address the issue as soon as possible to maintain the integrity of your Mercedes-Benz.

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