2021 Ford F-150 Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2021 Ford F-150 and How to Resolve Them

Find Repair Location
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 Ford F-150 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 Ford F-150 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 a rough idle in a 2021 Ford F-150?

When diagnosing a rough idle in a 2021 Ford F-150, it's essential to adopt a systematic approach that begins with the simplest checks before progressing to more complex diagnostics. Start by using an OBD-II scanner to check for any error codes, as these can quickly point you to specific issues within the engine. Next, inspect the spark plugs for wear or fouling, as faulty plugs can significantly affect idle quality. A clean air filter is also crucial; ensure it is free from debris to allow proper airflow. Additionally, examine the vacuum hoses for leaks, which can disrupt the air-fuel mixture and lead to rough idling. Don't overlook the fuel system; check the fuel filter and injectors for any malfunctions that could impact performance. Cleaning the throttle body can also help if carbon buildup is present. Lastly, ensure that the exhaust system is clear of restrictions and that coolant levels are adequate, as both can influence engine performance. By following this structured diagnostic approach, you can effectively identify and address the causes of a rough idle in your F-150.

What are the common problems that could cause a rough idle in a 2021 Ford F-150?

When dealing with a rough idle in a 2021 Ford F-150, it's essential to understand the common problems that could be contributing to this issue. 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, a faulty oxygen sensor can disrupt the delicate balance of the air-fuel mixture, resulting in rough idling. Vacuum leaks are another frequent issue, as they can create an improper air-fuel mixture that affects engine performance. Fuel system problems, such as a clogged fuel filter or malfunctioning fuel injectors, can also lead to rough idling by preventing the engine from receiving the proper amount of fuel. Furthermore, worn-out or fouled spark plugs can cause misfires, contributing to an unstable idle. Lastly, a malfunctioning throttle body, often due to carbon buildup or sensor issues, can exacerbate the problem. By identifying and addressing these common issues, you can effectively troubleshoot and resolve the rough idle in your Ford F-150, ensuring smoother engine performance.

How urgent is it to address the rough idle in a 2021 Ford F-150?

Addressing a rough idle in your 2021 Ford F-150 is not just a matter of comfort; it is crucial for the vehicle's overall health and performance. A rough idle can indicate underlying problems with critical systems such as the fuel or ignition systems, which, if left unchecked, may lead to decreased fuel efficiency and diminished engine performance. Moreover, ignoring this symptom can escalate into more severe issues, potentially resulting in costly repairs or even engine damage over time. The urgency to resolve a rough idle is heightened by the fact that it may also pose safety risks, as a malfunctioning engine can affect your vehicle's reliability on the road. Therefore, it is advisable to address any signs of a rough idle promptly to ensure your Ford F-150 operates smoothly and efficiently, ultimately saving you time and money in the long run.

You’ve got options with RepairPal

Whether you need a more accurate auto repair estimate or help finding a reputable shop in your area, we’ve got you covered.

Common Causes of Rough Idle in 2021 Ford F-150 | RepairPal