2021 Land Rover Discovery Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2021 Land Rover Discovery and How to Resolve Them

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Reviewed by
Andrew Hajjar
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 2021 Land Rover Discovery 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 2021 Land Rover Discovery 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 2021 Land Rover Discovery?

When faced with a rough idle in your 2021 Land Rover Discovery, it's crucial to adopt a systematic diagnostic approach. Start by checking for fault codes using a diagnostic scanner, as these codes can reveal specific issues within the vehicle's computer system. Next, inspect the spark plugs; they should be clean and functioning properly, as worn or fouled plugs can significantly impact engine performance. Don’t overlook the air filter; a clogged filter can restrict airflow, leading to an uneven idle. Additionally, examine the vacuum hoses for any signs of damage or leaks, as these can disrupt the air-fuel mixture. A thorough inspection of the throttle body is also essential; carbon buildup can hinder airflow and contribute to rough idling. Finally, ensure that the fuel system is operating correctly by checking the fuel filter and injectors, as any malfunction here can exacerbate idle issues. By following these steps, you can effectively diagnose and address the rough idle, potentially saving time and money on repairs.

What are the common problems that could cause a rough idle in a 2021 Land Rover Discovery?

When diagnosing a rough idle in a 2021 Land Rover Discovery, it's essential to consider several common problems that could be affecting the vehicle's performance. One of the primary culprits is a dirty or clogged air filter, which can restrict airflow to the engine, causing it to struggle to maintain a steady RPM. Additionally, faulty spark plugs may lead to misfiring, resulting in an uneven idle and diminished engine efficiency. Another potential issue is vacuum leaks, which can disrupt the air-fuel mixture and further exacerbate rough idling. Fuel system problems, such as a clogged fuel filter or a malfunctioning fuel pump, can also hinder proper fuel delivery, contributing to the issue. Furthermore, a faulty oxygen sensor can alter the air-fuel ratio, leading to rough idling and reduced fuel economy. Lastly, a malfunctioning throttle body, often due to carbon buildup or sensor issues, can disrupt airflow and cause similar symptoms. By addressing these common problems through regular maintenance and timely repairs, you can significantly improve the idle quality of your Land Rover Discovery.

How urgent is it to address the rough idle in a 2021 Land Rover Discovery?

Addressing a rough idle in your 2021 Land Rover Discovery should be treated with a sense of urgency, as it can indicate underlying engine problems that may escalate if ignored. A rough idle not only affects the vehicle's performance but can also lead to decreased fuel efficiency, which translates to higher operating costs over time. Moreover, neglecting this symptom could result in more severe engine damage, necessitating costly repairs that could have been avoided with timely intervention. While it may not seem like an immediate emergency, the potential risks to both your vehicle's health and your safety on the road make it crucial to have the issue diagnosed and resolved by a qualified mechanic as soon as possible. By addressing the rough idle promptly, you can ensure the longevity and optimal performance of your Land Rover, ultimately saving you time and money in the long run.

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2021 Land Rover Discovery Rough Idle Causes & Repairs