How to Fix Failing Audi A5 Xenon DRLs (2017-2020) – Light Guide & LED Board Replacement

TL;DR

The DRLs on the 2017-2020 Audi A5 with Xenon headlights commonly fail due to a burnt-out LED board or a cracked light guide, causing dim, flickering, or completely dead daytime running lights. The fix is replacing the Audi A5 Xenon DRL Light Guide Strip & LED Board (2017-2020), which restores full brightness and reliability.

What Goes Wrong with Audi A5 Xenon DRLs

These Audi models use a light guide strip that channels light from a small LED board to create the signature DRL signature. Over time, the LED board's solder joints can crack due to thermal cycling, or the light guide can become brittle and develop micro-cracks from UV exposure and road stress. This results in uneven illumination, flickering, or complete failure of the DRL. In many cases, the rest of the headlight (low beam, high beam) works fine, making it easy to misdiagnose.

How to Diagnose the Issue

Start by turning on the DRLs (ensure the light switch is in 'Auto' and the car is in daytime mode). Inspect the light strip visually: if one section is dark or visibly broken, it's the light guide. If the entire strip flickers or is dim, suspect the LED board. Also check for error codes with VCDS or OBDeleven – common codes include 'B11EA: Daytime running light left' or right. To confirm, you can swap the LED board from the left to the right headlight (if both are accessible) and see if the problem moves.

Step-by-Step Replacement

1. Remove the headlight assembly (unbolt the top and side brackets, then slide it forward). 2. Carefully separate the lens from the housing using a heat gun or oven (set to 150°F/65°C for 10-15 minutes) to soften the sealant. 3. Once open, disconnect the wiring harness and remove the existing light guide and LED board – they are typically clipped or screwed in place. 4. Install the new light guide and LED board, ensuring they are seated correctly. 5. Re-seal the lens using fresh butyl sealant or a headlight sealant kit. 6. Reinstall the headlight and test. Expect to spend 2-3 hours on the first attempt.

Fitment Tips & Expert Advice

When ordering, ensure you select the correct side (passenger/driver) and confirm it matches your Xenon headlight variant – not LED or Matrix. The replacement part is a direct OEM-style fit, but handle the light guide gently to avoid scratches. On these A5s the LED board is the more common failure point, but the light guide often yellows at the same time — which is why this kit includes both parts, so the headlight only has to be opened once.

FAQ

Q: How long do Audi A5 DRLs typically last? A: On average, the LED board can fail after 3-5 years, depending on usage and climate. Many owners report issues around the 40,000-mile mark.

Q: Can I drive with a failed DRL? A: Yes, but you'll fail inspections in many states/countries, and it reduces visibility to other drivers. Also, the error code may disable other headlight functions.

Q: Do I need to replace the whole headlight? A: No, a working light guide and LED board are much cheaper than a full headlight unit. Replacing just these parts takes about 2 hours if you're handy.

Q: Is this part compatible with all 2017-2020 A5 Xenon models? A: Yes, it fits the A5 Coupe, Sportback, and Cabriolet with Xenon headlights. If you have LED or Matrix headlights, this part won't fit.

Standards & further reading

Reference material for the standards and technology that govern vehicle lighting equipment:

• FMVSS No. 108 - Lamps, reflective devices, and associated equipment - the US federal standard governing vehicle lighting equipment - ams OSRAM - automotive lighting - light-source and LED technology reference - HELLA - automotive lighting and electronics - vehicle lighting systems reference

Standards reference: for the Audi A5 Xenon, the daytime running lamp is governed by UN ECE Regulation 148 (which superseded R87) in most markets and by FMVSS 108 in the United States - these define when the lamp runs and at what output. The swap reinstates exactly the behaviour those standards describe.