2018 Honda Fit Has Rough Idle

Causes of Rough Idling in Your 2018 Honda Fit and How to Resolve the Issue 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 2018 Honda Fit 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 2018 Honda Fit 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.

Customers with drum brake systems often specify they have lost braking power, or that the vehicle's brakes are making noise. This is because brake drums do not dissipate heat very well, so the heat from hard braking will cause stress fractures. These fractures make can make noise on the brake shoes as the drum revolves around the shoes. Lastly, the brake shoes may not be problematic, but may cause a grinding noise while stopping. This would indicate the shoes have no braking material left, and the brake shoes must be changed before the vehicle can be safely driven.

Learn more about brake shoe symptoms

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 and fix a rough idle in a 2018 Honda Fit?

When addressing a rough idle in your 2018 Honda Fit, it's crucial to follow a methodical diagnostic approach that begins with the simplest solutions. Start by utilizing an OBD-II scanner to check for error codes, as these can quickly point you to specific issues affecting your vehicle. Next, inspect the spark plugs for any signs of wear or damage, since faulty plugs can lead to significant performance problems. A clean air filter is essential for optimal airflow, so ensure it is free from dirt and debris. Additionally, examine the vacuum hoses for any leaks or cracks, as these can disrupt engine performance. The PCV valve should also be assessed, as a malfunctioning valve can contribute to rough idling. Cleaning the throttle body is another important step, as carbon buildup can impede its function. Don’t forget to check the fuel system, including the fuel filter and injectors, to ensure they are operating correctly. The EGR valve's functionality is also vital, so inspect it for any issues. Finally, consider the condition of the engine mounts, as worn mounts can create vibrations that mimic rough idling. If these preliminary checks do not resolve the issue, a compression test may be necessary to uncover any deeper internal engine problems. By systematically addressing these areas, you can effectively diagnose and remedy the rough idle in your Honda Fit.

What are the common causes of a rough idle in a 2018 Honda Fit?

When dealing with a rough idle in your 2018 Honda Fit, it's crucial to understand the common problems that could be at play. One of the first things to check is the air filter; a dirty or clogged filter can significantly restrict airflow to the engine, leading to performance issues. Additionally, inspect the spark plugs, as worn or faulty plugs can cause misfiring, which directly affects engine smoothness. Another area to investigate is the vacuum system for any leaks, as these can disrupt the air-fuel mixture and result in an unstable idle. Fuel system components, including the fuel filter and injectors, should also be examined, as clogs can hinder fuel delivery and impact engine performance. Furthermore, consider the ignition coils; if they are malfunctioning, they can lead to uneven engine operation. Lastly, a dirty or malfunctioning throttle body can impede proper air intake, contributing to a rough idle. By systematically checking these components, you can identify and address the underlying issues affecting your vehicle's performance.

How urgent is it to address the rough idle in my 2018 Honda Fit?

When it comes to addressing a rough idle in your 2018 Honda Fit, understanding the urgency of the situation is crucial for both safety and vehicle longevity. A rough idle can often signal underlying issues such as dirty fuel injectors or a clogged air filter, which, if left unattended, may lead to decreased fuel efficiency and engine misfires. These symptoms not only affect your driving experience but can also escalate into more serious problems, such as a failing ignition coil or a vacuum leak, which could result in costly repairs. By taking the time to diagnose and resolve these issues promptly, you can maintain the overall health of your vehicle, ensuring a smoother ride and prolonging its lifespan. Regular maintenance and timely repairs are key to preventing severe complications down the line, making it essential to address a rough idle sooner rather than later.

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