2013 Mercedes-Benz ML350 Has Rough Idle

Resolve Rough Idle in 2013 Mercedes-Benz ML350 for a Smoother Ride

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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 2013 Mercedes-Benz ML350 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 2013 Mercedes-Benz ML350 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 potential causes and diagnostic steps for a rough idle in a 2013 Mercedes-Benz ML350?

When dealing with a rough idle in your 2013 Mercedes-Benz ML350, it's essential to adopt a systematic diagnostic approach. Begin by inspecting for a vacuum leak, as this is often a straightforward issue that can significantly affect engine performance. Look for any damaged or worn vacuum hoses and connections, as even a small leak can disrupt the air-fuel mixture. Next, turn your attention to the spark plugs; these components are crucial for proper ignition and can wear out over time. Remove and examine them for signs of wear or fouling, and replace them if necessary to restore smooth operation. Finally, test the ignition coil, as a malfunctioning coil can lead to misfires and rough idling. By methodically addressing these potential causes, you can effectively diagnose and resolve the rough idle issue, ensuring your ML350 runs smoothly once again.

What are the common problems that could cause a rough idle in a 2013 Mercedes-Benz ML350?

When dealing with a rough idle in a 2013 Mercedes-Benz ML350, 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 necessary for smooth engine operation. Additionally, vacuum leaks in the intake system can create an imbalance, leading to erratic idling. Another critical component to check is the oxygen sensor; if it's malfunctioning, it can significantly impact engine performance. Dirty fuel injectors may also be a factor, as they can hinder proper fuel delivery, resulting in a rough idle. Furthermore, worn or faulty spark plugs can cause misfires, contributing to the issue. It's also worth examining the EGR valve, as problems here can disrupt engine performance at idle. Lastly, issues with the throttle body, such as carbon buildup or electronic malfunctions, can exacerbate rough idling. By systematically checking these components, DIYers can effectively diagnose and potentially resolve the rough idle issue in their ML350.

How urgent is it to address the rough idle in my 2013 Mercedes-Benz ML350?

Addressing a rough idle in your 2013 Mercedes-Benz ML350 is crucial for maintaining the vehicle's performance and longevity. A rough idle often indicates underlying problems such as faulty spark plugs, vacuum leaks, or issues within the fuel system, which, if left unattended, can escalate into more severe complications. Ignoring these symptoms not only risks decreased fuel efficiency and engine misfires but can also lead to significant damage to engine components over time. Regular maintenance and prompt repairs are essential to avoid costly fixes down the line. Therefore, it is highly advisable to diagnose and resolve the rough idle issue as soon as possible, ensuring your vehicle remains in optimal condition and safe to drive. Taking action now can save you from more extensive repairs and enhance your driving experience.

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