What Bulbs Are in the Audi A4?

The Audi A4 typically uses halogen, xenon (HID), or LED bulbs depending on model year, trim, and market, with common fitments including H7 and H11 for halogen headlights, D3S or D5S for xenon units, and sealed LED modules in newer models. Below is a detailed breakdown by generation and lighting type to help owners identify the correct bulbs and understand how Audi’s lighting technology has evolved.

Why Bulb Types Differ Across Audi A4 Models

The Audi A4 has been in production since the mid‑1990s, and its lighting technology has evolved from simple halogen headlights to advanced matrix LED systems. Bulb types vary by generation (B5–B10), trim (e.g., SE, S line, Technik), factory options (xenon, LED, matrix), and country regulations. That means two A4s from the same year can use very different bulbs if one has a lighting upgrade package and the other does not.

Key Headlight Bulb Types Used in the Audi A4

Most owners first want to know which bulbs handle low beam and high beam, since these are the most frequently replaced and upgraded. The list below outlines typical bulb types used in Audi A4 headlights, grouped by technology, but exact fitment can differ by region and equipment package.

• Halogen low beam: Commonly H7 (older B5–B8.5) or H11 in some markets and trims.
• Halogen high beam: Often H7, H9, or H15 (dual-function high beam/DRL in some models).
• Bi-xenon (HID) bulb: Frequently D1S, D3S, or D5S, depending on generation and lamp design.
• LED headlight modules: Integrated LED units (no simple “bulb”), introduced broadly from B9 (2016+) onward.
• Matrix LED / HD Matrix LED: Advanced, segmented LED modules with no user‑replaceable bulb.

While this overview reflects the most common bulb types, the exact code for your A4 may differ; owners should always confirm via the owner’s manual, the label on the headlamp housing, or a VIN‑based parts lookup.

By Generation: Typical Audi A4 Bulb Setups

Because bulb types changed over time, it’s useful to view them by generation. The following sections describe typical configurations found on European-spec and many global models; U.S. and other markets often follow similar patterns but can vary slightly.

B5 Audi A4 (1994–2001)

The first-generation A4 relied almost entirely on halogen lighting, with xenon available late in the cycle on certain trims. Below is a general guide to what most B5 owners will find.

• Low beam (halogen): H7 on most models.
• High beam: H1 or H7 depending on headlight unit supplier.
• Front indicators: PY21W amber bulbs.
• Front fog lights: H3 halogen bulbs in bumper-mounted housings (where fitted).
• Rear indicators: PY21W amber.
• Brake/tail lights: P21/5W dual‑filament.
• Reverse lights: P21W clear.
• Rear fog: P21W (in markets where required).

Owners of B5 models typically work with traditional halogen and standard incandescent bulbs throughout the car, making replacements inexpensive and straightforward.

B6 Audi A4 (2001–2005)

The B6 introduced more sophisticated lighting options, including factory xenon for low beam on certain trims, while many cars remained halogen-based. Here’s a typical breakdown.

• Low beam (halogen units): H7 bulbs.
• High beam (halogen units): H7 bulbs.
• Low beam (xenon units): D1S HID bulbs on many factory xenon setups.
• High beam with xenon: Separate H7 halogen high beam or bi-xenon shutter using the D1S bulb for both high and low.
• Front indicators: PY21W.
• Front fog lights: H11 or H7, depending on the bumper/fog lamp design.
• Brake/tail: P21/5W bulbs.
• Rear indicators, reverse, rear fog: Typically PY21W and P21W variants.

The B6 era began the shift toward HID on premium trims, so checking whether your car has xenon or halogen headlights is crucial before buying bulbs.

B7 Audi A4 (2004–2008)

The B7, a heavy facelift of the B6, continued with similar bulb technology but refined the lighting and made xenon more common. The bulb mix stayed broadly familiar.

• Low beam (halogen): H7 on most standard headlights.
• High beam (halogen): H7.
• Xenon low beam: Typically D1S or, in some configurations, D2S (region- and lamp-dependent).
• High beam with xenon units: H7 halogen high beam or bi‑xenon shutter using the xenon bulb.
• Front indicators: PY21W or silver‑coated PY21W (to reduce “egg yolk” look).
• Front fog lights: H11 in most markets.
• Brake/tail lights: P21/5W.
• Other rear bulbs: P21W (reverse, fog) and PY21W (indicator).

In practice, B7 owners usually contend with familiar H7 halogen and D1S xenon bulbs, plus standard incandescent bulbs at the rear, allowing easy upgrades to LED replacement bulbs where legally permitted.

B8 Audi A4 (2008–2015, including B8.5 facelift)

The B8 generation marked a major step up with more widespread bi-xenon and the introduction of LED daytime running lights (DRLs). However, many cars still use halogen headlights in base trims.

• Low beam (halogen setup): H7 bulbs.
• High beam (halogen setup): H7 or H9, depending on region and lamp type.
• Low beam (xenon/bi-xenon): Commonly D3S HID bulbs (especially post-facelift B8.5).
• High beam (bi-xenon): Bi-xenon shutter using the D3S bulb plus, in some trims, an auxiliary halogen high beam (H7/H9).
• Daytime running lights (DRL): LED strip or module integrated into the headlight; not a simple replaceable “bulb.”
• Front fog lights: H11 halogen bulbs on most models.
• Front indicators: PY21W or integrated into LED DRL modules on higher trims (especially with xenon).
• Rear lights (pre-facelift halogen clusters): P21/5W for brake/tail, PY21W for indicators, P21W for reverse and fog.
• Rear lights (LED clusters): LED modules for tail and brake; conventional bulbs (often P21W/PY21W) may remain for reverse and fog depending on version.

With the B8, A4 lighting became more complex: some functions moved to LED modules that are not user‑serviceable in the traditional sense, while key headlight functions still rely on replaceable HID or halogen bulbs.

B9 Audi A4 (2016–2023, including B9.5 facelift)

The B9 generation accelerated the move toward full LED and matrix systems. Halogen headlights largely disappeared in many markets, replaced by LED or xenon/LED hybrid setups, though some entry models in certain regions still had simpler units.

• Standard LED headlights (common in Europe and North America): Integrated LED modules for low and high beam; no traditional bulb for those functions.
• Matrix LED / HD Matrix LED: Advanced LED arrays for low/high beam and adaptive functions, fully integrated and not user‑replaceable as bulbs.
• Halogen variants (where fitted): Often H7 or H11 for low beam and H9/H15 for high beam/DRL, though these are less common.
• DRL/position lights: LED modules integrated into the headlight on virtually all B9 models.
• Front fog lights: In many B9s, the “fog” function is built into the main LED headlight or provided by cornering lights; in others, separate LED fog units are used.
• Rear lights: Largely LED for tail, brake, and indicators, with some models retaining conventional P21W bulbs for reverse lights.
• Dynamic rear indicators: Sequenced LED arrays (no bulb change possible, only module replacement).

For B9 owners, most external lighting except possibly the reverse lamp has transitioned to sealed LED systems, meaning traditional bulb shopping is usually limited to interior lights and a few remaining incandescent functions.

B10 / Latest Audi A4 (2024–present, including e-tron/fully electrified variants)

As Audi moves toward electrification and advanced driver-assistance, the latest A4 (and its successors, depending on market branding) feature near‑fully LED-based or even laser‑assisted systems at the top end. Conventional bulbs are now predominantly confined to a few minor functions.

• Main headlights: Standard LED or HD Matrix LED across most trims; no replaceable halogen or xenon bulbs.
• DRLs and position lights: Signature LED strips and light signatures, integrated modules.
• Rear lights: Full LED clusters with dynamic indicators and complex signatures.
• Reverse and rear fog lights: Often LED, though some market variants still use P21W or similar for reverse to simplify repairs.
• Auxiliary lighting: Side markers, license plate lamps, and some interior lamps may remain as W5W-type bulbs or LED festoons, depending on trim.

In the newest A4-based models, “bulb replacement” largely means replacing entire LED modules or light units, typically handled by a dealer or specialist rather than simple driveway work.

Common Audi A4 Bulbs by Function

While the exact bulb code can differ, certain bulb types appear repeatedly in A4 models for specific functions. The next list summarizes these by location so owners can quickly identify likely candidates before cross-checking with their VIN or manual.

• Low beam (halogen): H7 or H11 in most generations that use halogen headlights.
• High beam (halogen): H7, H9, or H15 (especially when combined high beam/DRL).
• Xenon (HID) low/bi-xenon: D1S, D2S, D3S, or D5S depending on generation and region.
• Fog lights: H3 (older B5), then mostly H11 on B6–B8; LED modules on B9+.
• Front indicators: PY21W incandescent or LED modules in later generations.
• Rear indicators: PY21W on halogen clusters; LED on later generations.
• Brake/tail lights: P21/5W on halogen clusters; integrated LEDs on higher trims and later generations.
• Reverse lights: P21W on many models; LED modules on current A4s.
• Rear fog lights: P21W or integrated LEDs.
• License plate lights: Festoon bulbs (e.g., C5W) on older cars; LED units on later generations.

These patterns mean that, for most non‑LED A4s, a small set of bulb types—H7, H11, PY21W, P21/5W, and P21W—will cover much of the car, though xenon and LED-equipped versions might use very few or none of these in the main light clusters.

Interior Bulbs in the Audi A4

Interior lighting in the A4 ranges from simple incandescent festoon bulbs in early cars to full LED ambient lighting in modern models. Although there is more variation here, several bulb styles are consistently used across generations.

• Dome/map lights (front and rear): Festoon bulbs (e.g., 36mm or 39mm C5W) or W5W wedge bulbs on older cars; LED modules on newer models.
• Glovebox light: Typically a W5W (T10 wedge) bulb on older A4s, often upgraded to LED.
• Trunk/boot light: Festoon bulb (C5W) or W5W; LED modules on recent A4s.
• Footwell lighting: W5W bulbs or small LED modules depending on trim and model year.
• Ambient lighting (door strips, dash accents): Factory LED light guides or modules, not discrete bulbs.

Because interior fitment can differ by trim package (e.g., ambient lighting packs), owners should pop the lens or check part numbers before ordering replacements, especially if upgrading to aftermarket LEDs.

How to Confirm the Correct Bulbs for Your Specific Audi A4

Given the number of options Audi offered over the years, even within the same generation, the safest approach is to verify bulb types directly for your exact car rather than relying solely on model‑year assumptions. The list below outlines reliable ways to do that.

1. Consult the owner’s manual: Most A4 manuals include a bulb chart listing each position (low beam, fog, brake, etc.) and the correct bulb code.
2. Check labels on the lamp housing: Many headlamp and rear lamp units carry molded or printed information showing bulb type (e.g., “H7,” “D3S,” “PY21W”).
3. Use a VIN-based parts catalog: Audi dealers and reputable online parts sites can decode your VIN and show the exact part numbers and bulb types for your build.
4. Physically inspect an existing bulb: Removing the current bulb and reading the markings (H7 55W, D3S, etc.) provides definitive confirmation.
5. Contact a dealer or specialist: For LED or matrix systems, a dealer or Audi specialist can identify whether any components are user‑serviceable and what replacements are needed.

By verifying bulb types through at least one of these methods, you greatly reduce the risk of ordering incompatible parts—especially important with pricier xenon and LED components.

Legal and Practical Considerations When Replacing Audi A4 Bulbs

Replacing or upgrading bulbs on an Audi A4 involves more than just fitment; legal regulations, on‑board diagnostics (OBD), and heat management can all affect your choice of replacement. The following points summarize what owners should keep in mind.

• Road legality of LED conversions: In many regions, fitting aftermarket LED bulbs into halogen housings (e.g., H7 LED replacements) is not road‑legal, even if they physically fit.
• CAN‑bus compatibility: The A4’s bulb monitoring system may flag errors if it detects unexpected resistance; “CAN‑bus friendly” bulbs or resistors may be required to prevent warning lights.
• Headlight alignment: Any change to headlight bulbs—especially retrofitting HID or LED into halogen units—can affect beam pattern and glare, requiring professional alignment and, in some cases, is not permitted at all.
• Heat and housing tolerance: Higher‑wattage bulbs or poorly designed LED/HID kits can overheat lenses or housings, leading to damage.
• Warranty and insurance: On newer A4s, modifications to factory lighting (particularly LED/matrix systems) can impact warranty coverage or complicate insurance claims if involved in a collision.

Considering these technical and legal aspects before changing bulbs helps ensure your A4 remains safe, compliant, and reliable while still achieving any desired improvements in visibility or aesthetics.

Summary

The bulbs in an Audi A4 range from simple halogen H7 and H11 lamps in early generations to D‑series xenon bulbs and, more recently, fully integrated LED and matrix LED modules. While older A4s (B5–B7) mostly rely on replaceable halogen and HID bulbs such as H7, PY21W, and D1S, the B8 generation added LED DRLs and more widespread bi‑xenon systems. From the B9 generation onward, many A4s use standard LED or matrix LED headlights and LED rear clusters, leaving only a few incandescent bulbs—often the reverse lights or some interior lamps—to be replaced by the owner. Because of the wide range of factory configurations, the most reliable way to identify the correct bulbs for any given A4 is to consult the owner’s manual, inspect the lamp housings, or use a VIN‑based parts catalog before buying replacements or upgrades.