2012 Mercedes-Benz CL65 AMG Has Rough Idle

Resolve Rough Idle in 2012 Mercedes-Benz CL65 AMG for a Smoother Ride

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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 2012 Mercedes-Benz CL65 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 2012 Mercedes-Benz CL65 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 initial diagnostic steps to take for a rough idle in a 2012 Mercedes-Benz CL65 AMG?

When addressing a rough idle in your 2012 Mercedes-Benz CL65 AMG, it's essential to adopt a systematic diagnostic approach that begins with the most straightforward checks. Start by using a diagnostic scanner to check for any fault codes stored in the vehicle's computer system, as these codes can pinpoint specific issues affecting engine performance. Next, inspect the spark plugs for wear or fouling, as these components play a crucial role in maintaining a smooth idle. Following this, evaluate the air intake system for any leaks or clogs that could disrupt the air-fuel mixture, and examine the vacuum hoses for cracks or disconnections that might impact engine performance. Additionally, testing the mass airflow sensor is vital, as a malfunction here can lead to incorrect air intake readings. Finally, don't overlook the fuel system; ensure that the fuel filter is clean and that the fuel injectors are functioning properly, as any blockages can hinder fuel delivery. By methodically working through these steps, you can effectively diagnose and address the rough idle issue in your vehicle.

What are the common causes of a rough idle in a 2012 Mercedes-Benz CL65 AMG?

When dealing with a rough idle in your 2012 Mercedes-Benz CL65 AMG, it's crucial to understand the common problems that could be at play. One of the primary culprits is dirty or faulty spark plugs, which can lead to engine misfires and an uneven idle. Additionally, vacuum leaks in the intake system can disrupt the delicate air-fuel mixture, exacerbating the roughness of the idle. Another potential issue is a malfunctioning mass airflow sensor, which plays a vital role in regulating the engine's air-fuel ratio; if it fails, you may notice a significant impact on performance. A clogged fuel filter can also restrict fuel flow, leading to rough idling, while a faulty oxygen sensor can throw off the fuel mixture, further contributing to the problem. Lastly, issues with the Exhaust Gas Recirculation (EGR) valve can create complications that manifest as a rough idle. By systematically checking these components, you can effectively diagnose and address the underlying issues, ensuring your vehicle runs smoothly once again.

How urgent is it to address the rough idle in my 2012 Mercedes-Benz CL65 AMG?

Addressing a rough idle in your 2012 Mercedes-Benz CL65 AMG is not just a matter of convenience; it is crucial for maintaining the overall health and performance of your vehicle. A rough idle can indicate serious underlying problems, such as misfiring cylinders or fuel system malfunctions, which, if left unattended, may lead to significant engine damage over time. Moreover, a vehicle that idles roughly often experiences decreased fuel efficiency and power output, which can hinder your driving experience. Safety is another critical factor; a rough idle can sometimes lead to stalling or hesitation during acceleration, posing a risk to you and others on the road. By addressing these symptoms promptly, you not only enhance your vehicle's performance but also potentially save on costly repairs in the future. Therefore, it is essential to take action as soon as you notice a rough idle to ensure your Mercedes-Benz remains in optimal condition.

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