The Audi A4 B9 is a compact executive car introduced in 2015 as part of Audi's fifth generation of the A4 lineup. Known for its modern design, advanced technologies, and impressive performance, the B9 variant quickly gained popularity among car enthusiasts.
This model features a sleek exterior, refined interior, and a range of powerful engine options that combine efficiency with dynamic driving. With its advanced LED lighting technology, the A4 B9 sets new standards in visibility and safety. However, as with any vehicle, issues like warning messages related to the lighting system can arise, requiring attention to ensure optimal functionality.
LED Headlamps
The Audi A4 B9 is equipped with state-of-the-art LED headlamps designed to provide superior illumination and enhance the overall driving experience. These headlamps include features like daytime running lights (DRLs), turn signals, and adaptive lighting technology. LED lights are more energy-efficient, durable, and brighter compared to traditional halogen or xenon bulbs, offering better visibility in all driving conditions.
The daytime running lights are particularly important as they ensure your vehicle is easily noticeable to other road users during the day, contributing significantly to safety.
What Does the Warning Message Mean?
When your Audi A4 B9 displays a message such as “Left side light/daytime running light defective” or “Right side light/daytime running light defective,” it indicates a malfunction in the front headlight system. Specifically, the side light or daytime running light (DRL) on the indicated side is defective and not functioning properly.
When this issue occurs, the affected light will no longer work, which can compromise your safety. Ignoring the warning can increase the risk of accidents. Therefore, it’s critical to address this issue as soon as possible by repairing or replacing the faulty component.
Common Audi Warning Messages Related to Lighting
Here are some of the most frequently seen lighting-related warning messages in Audi vehicles:
- Front Left turn signal defective. See owner's manual
- Front Right turn signal defective. See owner's manual
- Left side light/daytime running light defective. See owner's manual
- Right side light/daytime running light defective. See owner's manual
- Audi adaptive light: fault. See owner's manual
- Stand-/Tagfahrlicht links defekt. Siehe Bordbuch (Left side/daytime running light defective. See owner’s manual)
- Stand-/Tagfahrlicht rechts defekt. Siehe Bordbuch (Right side/daytime running light defective. See owner’s manual)
Each of these messages highlights specific issues in the lighting system that should not be overlooked, as they directly affect your vehicle's visibility and safety.
By promptly addressing any such warning messages, you can maintain the reliability of your Audi’s advanced lighting system and enjoy a safer driving experience. Always consult a trusted automotive technician or your local Audi service center to diagnose and resolve these issues effectively.
Why Did It Fail?
The failure of the side light or daytime running light on your Audi can typically be attributed to two main reasons: normal lifespan limitations or external damages.
- Normal Lifespan:
Every electronic component, including LED modules, has a finite lifespan. While LED lights are designed to last significantly longer than traditional bulbs, they are not immune to wear and tear. Over time, factors such as heat exposure, voltage fluctuations, or internal degradation can cause the LED module to fail, even under normal operating conditions. - External Damages:
External factors like physical damage or environmental conditions can also contribute to the malfunction of the LED module. For example:- Water or Moisture Intrusion: If the headlamp housing is compromised due to cracks or improper sealing, moisture can enter and damage the internal components, including the LED module.
- Accidents or Impacts: A collision or a minor impact can cause internal components to dislodge or short-circuit.
How to Fix It?
To resolve the defective side light or daytime running light warning, you will need to replace the faulty LED module with a compatible one. Here’s how to fix the issue:
- Purchase the Correct LED Module:
- It is crucial to purchase the exact replacement module that matches the part number of your faulty one. Incompatibility between part numbers can prevent the module from functioning correctly. For your Audi A4 B9, the 4M0907397AC Light Control Module (LCM) is a recommended replacement. You can find this part at Xenons4u, a trusted provider of high-quality automotive lighting components.
- Replace the Module:
- Carefully remove the defective module from the headlamp assembly following your vehicle’s repair manual, or consult a professional if unsure.
- Install the new module in its place, ensuring a secure and proper fit.
- No Diagnostic Reset Required:
- Once the new LED module is installed, the side light and daytime running lights should function normally.
- The warning message will automatically clear without requiring any additional diagnostic or coding work.
- Test the Lights:
- Turn on your vehicle and test the side light and daytime running light to confirm they are working correctly.
The compatible part numbers are listed as follows:
Audi part numbers:
- 4M0907397AC
- 4M0 907 397 AC
Hella part number:
- 011552-31AD
- 011552-31AC
- 01155231-AB
Compatible Audi A4 S4 RS4 8W B9 LED Headlamps
- Audi 8W0.941.034.A 8W0941034A
- AL 030129663200 0 301 296 632 00
- Audi 8W0.941.034.B 8W0941034B
- AL 030256023200 0 302 560 232 00
- Audi 8W0.941.034 8W0941034
- AL 030129623200 0 301 296 232 00
- Audi 8W0.941.033 8W0941033
- AL 030129623100 0 301 296 231 00
- Audi 8W0.941.773 8W0941773
- AL 145100011400 1 451 000 114 00
- Audi 8W0.941.774 8W0941774
- AL 030129623200 0 301 296 232 00
Compatible cars:
- Audi A4 S4 RS4 A4L B9 8W
- 2015 2016 2017 2018 2019 2020
- Sedan Saloon Avant Allroad Quattro Limousine
- 1.4 2.0 35 40 45 TFSI 2.9 V6 RS4 petrol gasoline
- 2.0 3.0 30 35 40 45 50 V6 TDI diesel
- S-Line Black Edition
