2024 Lexus RX350 Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2024 Lexus RX350 and How to Restore Smooth Performance

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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 2024 Lexus RX350 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 2024 Lexus RX350 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.

Brake caliper failure occurs in two different ways, and they create different symptoms.

The caliper can become stuck, in which case it won't release the brake pads. The seized caliper will cause the vehicle to brake constantly on one side, forcing the car to move toward that side. This pulling will be accompanied by a strong odor from one wheel.

Another way calipers fail is by leaking. If the caliper leaks, the brake pedal will feel too easy to push, and will sink all the way to the floor when held. Braking will become less effective the longer this goes on. There may also be brake fluid leaking onto the wheel.

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.

Brake rotors are mainly maintenance free, but when they have been subjected to abnormally hard use, the heat they absorb can cause the metal to turn blue, and cracking to occur. When this occurs, customers often specify they have lost braking power, or the vehicle's brakes are making noise. There may be no symptoms at all related to changing the brake rotors, since it is recommended to change brake rotors on most modern vehicles when performing a standard brake service.

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 2024 Lexus RX350?

When faced with a rough idle in your 2024 Lexus RX350, it's essential to adopt a systematic diagnostic approach to identify the root cause effectively. Start by checking the spark plugs, as worn or damaged plugs can lead to misfires, significantly affecting engine performance. Next, inspect the air filter; a clogged filter can restrict airflow, disrupting the air-fuel mixture and contributing to a rough idle. Following this, examine the fuel system components, including the fuel injectors and fuel filter, to ensure they are functioning correctly and delivering the necessary fuel to the engine. Utilizing an OBD-II scanner to check for error codes can provide valuable insights into any underlying issues that may not be immediately visible. Additionally, inspect the throttle body for cleanliness and functionality, as a dirty throttle body can hinder airflow. Lastly, check for any vacuum leaks in hoses and connections, as these can lead to performance issues. By methodically addressing these areas, you can effectively diagnose and potentially resolve the rough idle in your vehicle.

What are the common problems that could cause a rough idle in a 2024 Lexus RX350?

When dealing with a rough idle in your 2024 Lexus RX350, it's essential to understand the common problems that may be at play. One frequent culprit is a dirty or clogged air filter, which can significantly restrict airflow to the engine, leading to performance issues. Additionally, faulty spark plugs are notorious for causing misfires, which can manifest as a rough idle. Another area to inspect is the vacuum system; any leaks can disrupt the delicate air-fuel mixture, resulting in an uneven idle. Fuel system problems, such as a clogged fuel filter or malfunctioning fuel injectors, can also hinder engine performance and contribute to rough idling. Furthermore, a malfunctioning mass airflow sensor can throw off the engine's balance by causing it to run either too rich or too lean. Lastly, don't overlook the Exhaust Gas Recirculation (EGR) valve, as issues here can adversely affect the combustion process, leading to a rough idle. By addressing these common issues through regular maintenance and timely repairs, you can restore smooth operation to your vehicle.

How urgent is it to address the rough idle in a 2024 Lexus RX350?

Addressing a rough idle in your 2024 Lexus RX350 should be treated with urgency, as neglecting this symptom can lead to a cascade of more serious issues. A rough idle often signals underlying problems such as faulty spark plugs, fuel system malfunctions, or sensor failures, all of which are critical for your vehicle's performance. If left unchecked, these issues can escalate, resulting in decreased fuel efficiency, increased emissions, and potential engine damage, which can be costly to repair. Moreover, a rough idle can compromise your vehicle's safety and reliability, making it essential to diagnose and resolve the problem promptly. For DIY enthusiasts, starting with a thorough inspection of the spark plugs and fuel system can be a practical first step. Regular maintenance and timely repairs not only enhance your vehicle's longevity but also ensure a smoother driving experience, making it imperative to address any signs of a rough idle as soon as they arise.

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2024 Lexus RX350 Rough Idle Causes & Repairs | RepairPal