2016 Toyota Yaris Has Rough Idle

Causes of Rough Idling in Your 2016 Toyota Yaris 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 2016 Toyota Yaris has rough idle are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
  • Spark Plugs: A worn or fouled spark plug can cause misfires, rough idling, and decreased fuel efficiency due to incomplete combustion.
  • 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 2016 Toyota Yaris 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 a rough idle in a 2016 Toyota Yaris?

To effectively diagnose a rough idle in your 2016 Toyota Yaris, begin with the simplest checks to streamline the process. Start by connecting an OBD-II scanner to identify any trouble codes that may indicate specific issues. If no codes are present, shift your attention to inspecting the vacuum lines for leaks, as these can significantly impact engine performance. Next, examine the throttle body and Mass Airflow (MAF) sensor for cleanliness and proper function, as dirt or malfunction can disrupt airflow and fuel mixture. Don’t overlook the spark plugs; worn or damaged plugs can lead to misfires and rough idling, so inspect them closely. Additionally, testing the fuel pressure with an in-line gauge will help determine if the fuel system is delivering adequate pressure. Finally, consider the ignition coil, as faults here are common culprits of rough idling. By following this structured diagnostic approach, you can efficiently identify and address the underlying issues affecting your vehicle's performance.

What are the common problems that could cause a rough idle in a 2016 Toyota Yaris?

When dealing with a rough idle in your 2016 Toyota Yaris, it's crucial to understand the common problems that may be at play. One of the primary culprits is a vacuum leak, which can disrupt the delicate balance of the air-fuel mixture, leading to an unstable idle. Additionally, worn or faulty spark plugs can cause misfiring, further exacerbating the rough idle condition. Another potential issue is a malfunctioning ignition coil, which plays a vital role in the ignition process. Beyond these, a dirty or faulty Mass Airflow Sensor (MAF) can significantly impact engine performance by misreading the air entering the engine, thus affecting the air-fuel mixture. Other components, such as the head gasket, fuel pump, engine coolant temperature sensor, and idle air control valve, can also contribute to rough idling. By identifying and addressing these common problems, you can restore your Yaris to smooth operation and prevent more serious complications down the line.

How urgent is it to address the rough idle in a 2016 Toyota Yaris?

Addressing a rough idle in your 2016 Toyota Yaris is more urgent than it may initially seem. This symptom can indicate underlying issues such as a vacuum leak, faulty spark plugs, or malfunctioning ignition coils, which, if left unresolved, can escalate into more severe problems. Ignoring a rough idle not only compromises your vehicle's performance but can also lead to increased emissions and reduced fuel efficiency, ultimately affecting your wallet. Moreover, a poorly running engine may stall unexpectedly, posing safety risks on the road. To ensure the longevity of your Yaris and avoid costly repairs, it is crucial to conduct preventive maintenance and consult a mechanic to diagnose the specific cause of the rough idle. By addressing this issue promptly, you can maintain optimal vehicle performance and safety, making it a priority for any DIY enthusiast.

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