2017 Audi A4 Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2017 Audi A4 and How to Restore Smooth Performance

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Reviewed by
Aisha
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 2017 Audi A4 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 2017 Audi A4 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 2017 Audi A4?

To effectively diagnose a rough idle in your 2017 Audi A4, start with a systematic approach that prioritizes simpler checks before delving into more complex diagnostics. Begin by using an OBD-II scanner to check for any fault codes, as these can quickly point you to specific issues within the vehicle's systems. Next, inspect the spark plugs for wear or fouling, since these components are crucial for proper ignition and can lead to misfires if compromised. Following this, examine the ignition system, including coils and wires, to ensure they are functioning correctly, as any faults here can contribute to an unstable idle. After addressing these initial components, turn your attention to the air intake system, checking for leaks or blockages that could disrupt the air-fuel mixture. A thorough inspection of the fuel system is also essential; ensure that the fuel injectors, filter, and pump are all operating as they should. Additionally, evaluate the EGR valve, as a malfunctioning valve can significantly impact engine performance. Finally, don’t overlook the vacuum hoses; any cracks or leaks can lead to performance issues and should be repaired. By following this structured diagnostic approach, you can effectively identify and resolve the underlying causes of a rough idle in your Audi A4.

What are the common problems that could cause a rough idle in a 2017 Audi A4?

When dealing with a rough idle in a 2017 Audi A4, it's essential to consider several common problems that could be at play. One of the primary culprits is a dirty or faulty mass airflow sensor, which can disrupt the delicate balance of the air-fuel mixture, leading to an unstable idle. Additionally, vacuum leaks can create an improper air-fuel ratio, further exacerbating the rough idle issue. Worn-out spark plugs or malfunctioning ignition coils are also significant factors, as they can cause engine misfires that manifest as a rough idle. Another potential issue is a clogged fuel filter, which restricts fuel flow and negatively impacts engine performance. Furthermore, problems with the Exhaust Gas Recirculation (EGR) valve can disrupt engine operation, affecting idle quality. Lastly, a malfunctioning throttle body can interfere with air intake, contributing to an uneven idle. By understanding these common problems, DIYers can take the necessary steps to troubleshoot and address the rough idle in their Audi A4 effectively.

How urgent is it to address the rough idle in my 2017 Audi A4?

Addressing a rough idle in your 2017 Audi A4 is crucial for maintaining the vehicle's performance and preventing further complications. A rough idle can indicate serious underlying issues such as faulty spark plugs, vacuum leaks, or fuel system malfunctions. If left unattended, these problems can escalate, leading to decreased fuel efficiency, engine misfires, and even significant damage to engine components. The longer you wait to address a rough idle, the more likely you are to face costly repairs down the line. Regular maintenance and timely intervention not only enhance your vehicle's longevity but also ensure a safer driving experience. Therefore, it is essential to prioritize resolving a rough idle as soon as you notice it, safeguarding both your Audi's performance and your investment.

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