2003 Audi S8 Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your 2003 Audi S8 and How to Fix Them

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Reviewed by
Devin Cabugcal
Written by RepairPal Car Genius
Updated January 14, 2025
0%
30% chance it's the
Sensor
0%
25% chance it's the
Control Module
0%
25% chance it's the
Throttle
0%
20% chance it's
Something else
The most common reasons a 2003 Audi S8 cruise control isn't working are failed control module, sensor or switch issues, or throttle actuation problems.
  • Sensor: A faulty or malfunctioning sensor can lead to incorrect readings, causing issues with engine performance or other systems relying on accurate data.
  • Control Module: A faulty control module can lead to erratic vehicle behavior or failure of various electronic systems due to improper signal processing.
  • Throttle: A faulty throttle body or a defective accelerator pedal position sensor may be causing inconsistent throttle response.
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 2003 Audi S8 cruise control isn't working?

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.

When the vehicle speed sensor fails or the wiring harness prevents signal transmission, the speedometer is the first thing that will stop functioning properly. This can be an intermittent issue where the speedometer only works occasionally, the speedometer may cease all function, or the speedometer may read erratically or incorrectly. Also, the traction control and anti lock brake warning lights specific to each vehicle may be illuminated, depending on the design of those systems. You may notice the vehicle hesitate to accelerate, cruise control will not function properly, and the vehicle may not shift properly through all of the gears.

In the event that a wheel speed sensor fails, the ABS, traction control system (TCS) and manufacturer specific stability control system lights will illuminate, informing the driver that the systems are disabled. The vehicle will be more prone to tire slip, and normal driving patterns may need to be adjusted to correct for the loss of computer control. On older vehicle's, the speedometer can be affected, causing illumination of the check engine light as well.

What are the initial diagnostic steps to troubleshoot the non-functional cruise control in a 2003 Audi S8?

When faced with a non-functional cruise control in your 2003 Audi S8, start your troubleshooting process by checking the fuse box to ensure the cruise control fuse is intact. A blown fuse is a simple fix that can often resolve the issue. Next, inspect the cruise control switch located on the steering wheel; ensure it is functioning properly, as a malfunctioning switch can prevent the system from engaging. It's also crucial to verify that your brake lights are operational, since a faulty brake light switch can inadvertently disable the cruise control system. Additionally, examine the throttle cable and linkage for any obstructions or issues that might hinder the cruise control's functionality. Finally, consider scanning your vehicle's onboard computer system for any error codes that may provide insight into the problem. By systematically following these steps, you can effectively diagnose and potentially resolve the cruise control issue in your Audi S8.

What are the common problems that could cause the cruise control to stop working in a 2003 Audi S8?

When dealing with a non-functional cruise control system in a 2003 Audi S8, it's crucial to understand the common problems that may be at play. One of the first areas to check is the cruise control switch, as a faulty switch can prevent the system from engaging or disengaging properly. Additionally, the brake light switch is another critical component; if it is defective, it may inadvertently deactivate the cruise control when the brakes are applied, leading to frustrating interruptions. Another potential culprit is vacuum leaks within the system, which can cause a loss of pressure and hinder the cruise control's ability to maintain speed. Furthermore, a malfunctioning speed sensor can result in inaccurate speed readings, directly impacting the cruise control's performance. Lastly, don't overlook electrical issues, such as blown fuses or wiring problems, which can disrupt the entire system. By systematically checking these components, DIYers can effectively diagnose and address the cruise control issues in their Audi S8.

How urgent is it to repair the non-functioning cruise control in a 2003 Audi S8?

Repairing the non-functioning cruise control in a 2003 Audi S8 should be viewed as a priority, albeit not an immediate emergency. The absence of this feature can compromise safety by increasing driver fatigue during long drives, as maintaining a consistent speed becomes more challenging. Additionally, the convenience of cruise control enhances the overall driving experience, particularly on highways, where it allows for a more relaxed journey. Furthermore, from a financial perspective, ensuring that all vehicle features are operational can significantly impact the resale value. Prospective buyers often look for well-maintained vehicles with all functionalities intact. Therefore, while the car remains operational without cruise control, addressing this issue promptly is advisable to enhance safety, improve comfort, and protect the vehicle's value in the long run.

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