2013 Mercedes-Benz C300 Has Rough Idle

Resolve Rough Idle in 2013 Mercedes-Benz C300 for a Smoother Ride

Find Repair Location
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 C300 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 C300 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 2013 Mercedes-Benz C300?

When faced with a rough idle in your 2013 Mercedes-Benz C300, it's essential to adopt a systematic 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 vehicle's systems. Next, inspect the spark plugs; ensuring they are clean and functioning properly is crucial, as worn plugs can significantly affect engine performance. Don't overlook the air filter; a clogged filter can restrict airflow, leading to an uneven idle. Additionally, examine the vacuum lines for any leaks, as these can disrupt the air-fuel mixture and exacerbate idle problems. It's also wise to assess the fuel system, including the fuel filter and injectors, to ensure they are delivering the right amount of fuel to the engine. Finally, take a look at the throttle body for any buildup that could hinder its operation. By following these steps, you can effectively diagnose and address the rough idle issue, potentially saving time and money on repairs.

What are the common problems that could cause a rough idle in a 2013 Mercedes-Benz C300?

When dealing with a rough idle in your 2013 Mercedes-Benz C300, 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 air and fuel entering the engine, leading to an uneven idle. Additionally, vacuum leaks can create an improper air-fuel mixture, exacerbating the rough idle issue. It's also crucial to inspect the spark plugs and ignition coils, as worn components can cause misfires that contribute to an unstable idle. A clogged fuel filter may restrict fuel flow, further impacting engine performance, while issues with the idle air control valve can disrupt the engine's idle speed. Lastly, a malfunctioning throttle body can hinder air intake, resulting in a rough idle. By systematically checking these components, you can effectively diagnose and address the root cause of the rough idle in your vehicle, ensuring a smoother driving experience.

How urgent is it to address the rough idle in my 2013 Mercedes-Benz C300?

Addressing a rough idle in your 2013 Mercedes-Benz C300 is not just a matter of comfort; it is crucial for the overall health of your vehicle. A rough idle can signal serious underlying problems, such as engine misfires or issues with fuel delivery, which, if left unchecked, can escalate into more significant and costly repairs. Moreover, neglecting this symptom can lead to decreased fuel efficiency, resulting in higher operating costs over time. The urgency to act is further underscored by the potential safety risks associated with engine performance issues, which could compromise your vehicle's reliability on the road. By prioritizing timely maintenance and repairs, you not only enhance the longevity of your C300 but also safeguard against the risk of more severe damage that could arise from ignoring these warning signs. Therefore, if you notice a rough idle, it is essential to investigate and address the issue promptly to maintain optimal performance and ensure your safety.

You’ve got options with RepairPal

Whether you need a more accurate auto repair estimate or help finding a reputable shop in your area, we’ve got you covered.