2023 Lexus LC500h Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2023 Lexus LC500h and Solutions for a Smoother Ride

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Reviewed by
Devin Cabugcal
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 2023 Lexus LC500h 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 2023 Lexus LC500h 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 steps to diagnose the rough idle in a 2023 Lexus LC500h?

When diagnosing a rough idle in a 2023 Lexus LC500h, it's crucial to follow a structured diagnostic approach that prioritizes simpler checks before delving into more complex issues. Begin by verifying whether the check engine light is on; if it is, utilizing an OBD-II scanner can help you retrieve error codes that indicate specific problems. Next, inspect the spark plugs for any signs of wear or fouling, as these can significantly affect engine performance. A clean air filter is essential for proper airflow, so ensure it is free from dirt and debris. Additionally, examine the vacuum hoses for any cracks or disconnections, as leaks can disrupt engine function. Cleaning the throttle body is another important step, as carbon buildup can interfere with the air-fuel mixture. Don't forget to check the fuel system for clogged injectors or a faulty fuel pressure regulator, as these issues can also lead to rough idling. The idle air control valve should be inspected for malfunctions or carbon buildup that may affect its operation. If the rough idle persists after these checks, performing a compression test can help identify deeper issues within the engine's internal components. By systematically addressing these areas, you can effectively diagnose and resolve the rough idle in your Lexus LC500h.

What are the common problems that could cause a rough idle in a 2023 Lexus LC500h?

When dealing with a rough idle in your 2023 Lexus LC500h, it's essential to consider several common issues that could be affecting your vehicle's performance. One of the primary culprits is a dirty or clogged air filter, which can significantly restrict airflow to the engine, leading to an uneven idle. Additionally, faulty spark plugs are notorious for causing misfires, which can also contribute to a rough idle. Another potential issue is vacuum leaks; these can disrupt the delicate air-fuel mixture necessary for smooth engine operation. Problems within the fuel system, such as a clogged fuel filter or a malfunctioning fuel pump, can further exacerbate idle issues by affecting fuel delivery. Moreover, a faulty oxygen sensor can throw off the air-fuel ratio, resulting in performance problems, including rough idling. Lastly, a malfunctioning throttle body, often due to carbon buildup or sensor issues, can lead to irregular engine behavior. By understanding these common problems, you can take proactive steps to diagnose and resolve rough idle issues, ensuring your Lexus runs smoothly. Regular maintenance and timely repairs are key to keeping your vehicle in optimal condition.

How urgent is it to address the rough idle in a 2023 Lexus LC500h?

Addressing a rough idle in your 2023 Lexus LC500h should be treated with urgency, as it can signal underlying engine problems that may escalate if left unattended. A rough idle not only affects the smooth operation of your vehicle but can also lead to decreased fuel efficiency and increased wear on engine components. Ignoring this symptom could result in more severe issues, such as damage to the spark plugs, fuel system, or critical sensors, which are essential for optimal vehicle performance. Regular maintenance and prompt repairs are key to preventing costly repairs down the line, making it crucial to take action as soon as you notice any irregularities in your vehicle's idling. By addressing a rough idle promptly, you can ensure the longevity and reliability of your Lexus LC500h, safeguarding both your investment and your driving experience.

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2023 Lexus LC500h Rough Idle: Causes & Repair Costs