2019 Mercedes-Benz GLC43 AMG Has Rough Idle

Resolve Rough Idle in 2019 Mercedes-Benz GLC43 AMG for a Smoother Ride

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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 2019 Mercedes-Benz GLC43 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 2019 Mercedes-Benz GLC43 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.

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 2019 Mercedes-Benz GLC43 AMG?

When faced with a rough idle in your 2019 Mercedes-Benz GLC43 AMG, it's essential to adopt a methodical diagnostic approach to identify the root cause. Start by checking for fault codes using a diagnostic scanner, as these codes can reveal specific issues within the engine management system. Next, inspect the spark plugs; worn or damaged plugs can significantly affect engine performance and contribute to an unstable idle. Following this, examine the air filter for dirt or clogs, as restricted airflow can lead to poor engine operation. Additionally, inspect the vacuum hoses for any signs of leaks or damage, which can disrupt the air-fuel mixture and exacerbate idle problems. It's also crucial to assess the fuel system, including the fuel pump, injectors, and filter, as any malfunction here can directly impact engine performance. Finally, take a look at the throttle body for carbon buildup or dirt, as a clean throttle body is vital for maintaining smooth idle quality. By systematically addressing these areas, you can effectively diagnose and potentially resolve the rough idle issue in your vehicle.

What are the common problems that could cause a rough idle in a 2019 Mercedes-Benz GLC43 AMG?

When dealing with a rough idle in your 2019 Mercedes-Benz GLC43 AMG, 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 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 rough idle issue. Worn or faulty spark plugs are another frequent cause, as they can lead to engine misfires that manifest as rough idling. A clogged fuel filter may also restrict fuel flow, impacting engine performance and contributing to the problem. Furthermore, malfunctioning oxygen sensors can alter the air-fuel mixture, resulting in poor engine performance and rough idling. Lastly, issues with the throttle body, such as carbon buildup or component failure, can disrupt airflow and lead to similar symptoms. By identifying and addressing these common issues, you can effectively restore smooth idling to your vehicle, ensuring a better driving experience.

How urgent is it to address the rough idle in a 2019 Mercedes-Benz GLC43 AMG?

Addressing a rough idle in your 2019 Mercedes-Benz GLC43 AMG should be treated as an urgent matter, as neglecting this symptom can lead to serious consequences for both your vehicle's performance and your safety. A rough idle often signals underlying issues such as problems with the spark plugs, fuel system, or engine sensors, which, if left unresolved, can escalate into more significant mechanical failures. This not only compromises the efficiency of your vehicle, leading to increased fuel consumption, but can also result in costly repairs down the line. For DIY enthusiasts, it’s crucial to recognize that timely intervention can prevent further damage and ensure the longevity of your vehicle. Regular maintenance and prompt attention to symptoms like a rough idle are essential practices that can save you time and money while keeping your Mercedes-Benz running smoothly.

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2019 Mercedes-Benz GLC43 AMG Rough Idle Causes & Solutions