2013-2017 Audi A4, A5, Q5 & More Headlight Switch Guide: Diagnosing Failures & Choosing the Right Part
This guide covers common failures, replacement, and how to choose the correct used headlight switch for your 2013-2016 A4/S4/Allroad, 2013-2017 A5/S5/Q5/SQ5, or 2013-2015 RS5.
- The most critical factor when buying a replacement is matching the 'AUTO' headlight function. If your car has it, the new switch must have it.
- Failure symptoms include lights turning on by themselves, flickering, and intermittent operation.
- Replacement is extremely easy and requires no tools. Just push the knob in, turn it, and pull the entire unit out.
- Before replacing the switch, check for simple electrical issues like bad grounds or corroded fuse box connections, which can cause similar symptoms.
Symptoms of a Failing Headlight Switch
A faulty headlight switch on these Audi models can cause a range of confusing and often intermittent electrical issues. Because it's an electronic module, symptoms can be more complex than simply having lights that don't turn on. Owners most frequently report issues that appear randomly.
- Lights Turn On By Themselves: You may find your parking lights or headlights have turned on by themselves, even with the vehicle turned off and locked. This is a classic sign of an internal short circuit in the switch module.
- Intermittent or Erratic Operation: The headlights, fog lights, or dashboard lights may flicker, or fail to turn on or off consistently. The switch might only work in certain positions, or you may have to jiggle it to get the lights to respond.
- Switch Feels Loose or Worn: The rotary knob may feel loose, gritty, or lack a positive 'click' between positions. While cosmetic wear is normal, a physically loose or sloppy switch can indicate internal mechanical failure.
- High Beams Won't Stay On: While less common for this rotary switch design, a related internal failure can affect the high beam function, preventing them from staying engaged.
- Burning Plastic Smell: A faint smell of burning plastic coming from the dashboard area when you operate the lights is a major red flag. This indicates the switch is overheating and could be a fire hazard. Stop using the vehicle and inspect the switch immediately.
Pro Tip: Electrical issues can be tricky. Before condemning the switch, check for corroded connections in the fuse box or worn wiring in the harness leading to the switch, as these can cause similar symptoms. Also, a "Dipped Headlight" warning on the dash is often caused by a failing HID bulb or ballast, not the switch itself.
Known Issues, Recalls, and Technical Service Bulletins (TSBs)
While this headlight switch is generally reliable, there is one notable recall for this vehicle generation that involves the lighting software.
NHTSA Recall 16V-642 (Audi Campaign 97CB)
This recall affects certain 2017 Audi A4, Q7, and 2016-2017 TT models, among others. The issue is a software error that causes the side marker lights to not illuminate when the parking lights are on and the vehicle is locked. This reduces the vehicle's visibility at night, increasing crash risk. The fix is a simple software update performed by an Audi dealer and does not involve replacing the headlight switch itself.
Buying a Used Headlight Switch: The Definitive Checklist
Purchasing a used OEM headlight switch is a smart way to save money, as they are significantly cheaper than new dealer parts and generally more reliable than low-cost aftermarket versions. However, you MUST verify you are buying the correct version for your car's options.
The #1 Most Important Check: 'AUTO' Function
The biggest difference between these switches is the presence of the 'AUTO' headlight function. This feature uses a light/rain sensor (usually located on the windshield near the rearview mirror) to turn the headlights on automatically.
- If your current switch has an 'AUTO' position: You MUST buy a replacement switch that also has the 'AUTO' position. Part numbers like 8K0941531AS are for vehicles with this feature.
- If your current switch does NOT have an 'AUTO' position: You must buy a replacement that also lacks this feature.
Warning: Installing a switch with the 'AUTO' function on a car not equipped with the necessary sensor will not add the feature and may cause unpredictable behavior or fault codes. Always match the switch to your vehicle's factory options.
Physical Inspection Checklist
- Check the Part Number: While there are many revisions, matching the primary part number (8K0941531) and the 'AUTO' function is the most critical step. Common part numbers include 8K0941531AS, 8K0941531AL, and 8K0941531AR.
- Inspect the Knob and Graphics: Look for a switch with clear, unworn graphics. The chrome trim ring should be intact and not peeling. This indicates it came from a well-kept vehicle.
- Test the Feel: If possible, turn the knob. It should have a distinct, crisp click for each position. It should not feel loose or gritty.
- Examine the Connector: Check the electrical connector pins on the back. They should be straight, clean, and free of any corrosion or signs of overheating (discoloration, melted plastic).
Cost Comparison: New vs. Used Headlight Switch
| Part Type | Estimated Cost |
|---|---|
| New OEM (Dealer) | $100 - $130 |
| New Aftermarket | $15 - $45 |
| Used OEM (Recycled) | $25 - $60 |
| Shop Labor Cost | $50 - $125 |
Replacement Guide (DIY Difficulty: 1/5)
Replacing this headlight switch is one of the easiest repairs you can perform on these vehicles. It requires no tools and takes less than two minutes.
🎬 Watch this quick video on how to remove the switch.- Release the Switch: In the 'Off' or '0' position, firmly push the center of the rotary knob inward until it clicks and stays depressed.
- Turn and Pull: While the knob is pushed in, turn it slightly clockwise (to the right) about 15-20 degrees. You will feel the internal locking tabs retract. Pull the entire switch assembly straight out of the dashboard.
- Swap the Connector: Press the release tab on the electrical harness and unplug it from the back of the old switch. Plug the harness into your new switch; it only fits one way.
- Install the New Switch: Align the new switch assembly with the opening in the dashboard and push it straight in until it clicks securely into place. Test all lighting functions to confirm the repair. 🎬 See a step-by-step replacement for A4, A5, and Q5 models.
Frequently Asked Questions
Why is my headlight switch knob pushed in and stuck?
It is not broken or stuck. On many Audi models, this is a built-in safety feature designed to allow the knob to retract during a collision to prevent injury to the driver's knee. To fix it, simply grip the knob firmly and pull it straight out. It will click back into its normal operating position.
🎬 Watch how to easily fix a stuck or retracted knob.Can I upgrade to a switch with the 'AUTO' headlight function?
No, not by simply swapping the switch. The 'AUTO' function requires a specific rain and light sensor that is mounted to the windshield. If your vehicle did not come with this feature from the factory, just installing the switch will not make it work.
Does a replacement headlight switch need to be programmed?
No. As long as you are replacing your old switch with a compatible new or used one (matching the 'AUTO' feature), no programming or coding is required. It is a direct plug-and-play replacement.
My lights still act strange after replacing the switch. What's next?
If a new switch doesn't solve the problem, the fault likely lies elsewhere in the electrical system. The most common culprits are a poor ground connection, corrosion in a fuse box, or a damaged wiring harness between the switch and the Body Control Module. These issues may require more in-depth professional diagnosis.
Helpful Videos
Technical Specifications
OEM Part Numbers: 8K0941531AS 8K0941531ASWEP 8K0941531AL 8K0941531ALWEP 8K0941531AQ 8K0941531AR 8K0941531ARWEP 8K0941531AK 8K0941531AA
Rotary control switch with integrated pull function for fog lights. Available in two main variants: with or without the 'AUTO' headlight setting.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Audi A4:
- Audi A5:
- Audi Q5:
- Audi S4:
- Audi S5:
- Audi RS5:
- Audi SQ5:
- Audi Allroad:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Symptoms of a Failing Headlight Switch
- Known Issues, Recalls, and Technical Service Bulletins (TSBs)
- NHTSA Recall 16V-642 (Audi Campaign 97CB)
- Buying a Used Headlight Switch: The Definitive Checklist
- The #1 Most Important Check: 'AUTO' Function
- Physical Inspection Checklist
- Cost Comparison: New vs. Used Headlight Switch
- Replacement Guide (DIY Difficulty: 1/5)
- Frequently Asked Questions
- 🎟️ Get 5% Off