There is no single bulb map that fits every vehicle. The correct bulb type and its location depend on the make, model, and year of your car; your owner's manual or the headlight diagram is the authoritative source. Replacements must use the exact base and rating specified for your vehicle.
Identify the correct bulb for your vehicle
Use the following steps to determine the precise bulb designations for your car and ensure you purchase the right replacements.
- Check the vehicle’s owner's manual or the factory headlight diagram for the exact bulb numbers (for example, H7, H11, 9005, D3S, etc.).
- Inspect the current bulb or the connector on the headlight housing to read the base type and size printed on the base.
- Note the function each bulb serves (low beam, high beam, fog light, etc.) since different functions use different bulb types.
- If the manual isn’t readily available, use the vehicle’s make, model, and year to search the manufacturer’s catalog or an auto parts site for the correct bulb size and function.
- Bring the old bulb or the bulb base to a parts store to confirm a proper match and avoid ordering errors.
Once you know the exact base and function, you can buy the correct bulb and follow the replacement steps in your manual to install it safely.
Common bulb types and typical locations
Below is a general guide to the bulb bases most commonly used for headlight functions. Vehicle-specific variations exist, so always verify with your manual or a parts lookup for your exact year and market.
- Halogen bulbs
- H4 (dual-beam): used for combined low/high beams on many older vehicles.
- H7: common for single low-beam or high-beam in many European cars).
- H11: frequently used for low-beam headlights or some fog lights.
- 9005 (HB3): often the high-beam bulb on many cars.
- 9006 (HB4): used as low-beam on some models or as fog light on others.
- H13 (9008): dual-beam in some modern setups.
- Fog light bulbs
- Common bases include H8, H9, H11, and various 900x variants depending on the model.
- Xenon/HID bulbs
- D2S, D3S, or D4S: HID projectors commonly used in factory-installed systems; require a ballast and proper housing.
- Note: HID bulbs are not interchangeable with halogen bulbs and often cannot be replaced with a simple bulb swap.
- LED headlights
- Many newer vehicles use LED modules or bulbs with fixed bases; replacement may involve entire bulbs or modules rather than traditional halogen bulbs.
- Ensure compatibility with your headlight housing, driver electronics, and CAN bus system to avoid warnings or performance issues.
In all cases, the exact bulb type and its function should be confirmed against your vehicle’s documentation or a reliable parts lookup for your specific model.
Special cases: HID/LED and daytime running lights
HID and LED headlights behave differently from standard halogen bulbs, and daytime running lights (DRLs) are often a separate system. Understanding these differences helps avoid mistakes during replacement.
- HID headlights require a ballast and correct bulb type; mixing with halogen can damage the electrical system and reduce performance.
- LED headlights may be integrated modules; some vehicles require a complete assembly or a CAN-bus compatible replacement to avoid warning lights or misbehavior.
- DRLs are frequently dedicated lighting circuits and may use different bulb types or LED modules; replacing them can require model-specific parts.
In short, HID/LED systems are not always interchangeable with halogen bulbs, and DRLs often demand unique components. Always verify compatibility with your vehicle’s documentation or a professional installation service.
Safety and replacement tips
Follow these best practices to replace headlight bulbs safely and effectively without damaging your vehicle or compromising visibility.
- Power off the vehicle and remove the key; disconnect the battery if you’re working near electrical connectors.
- Allow bulbs to cool before touching them to avoid burns.
- Wear gloves or use a clean cloth to prevent skin oils from shortening bulb life or causing hot spots on halogen bulbs.
- Handle bulbs by the base, not the glass; install them securely and avoid forcing connectors.
- After installation, test all headlights and aim/adjust the beams according to the manufacturer’s specifications to prevent glare for oncoming drivers.
If you’re unsure about the process or dealing with HID/LED systems or DRLs, seek professional assistance to ensure proper alignment and electrical safety.
Summary
There is no universal mapping for which headlight bulb goes where. The correct bulb depends on your specific vehicle and function (low beam, high beam, fog light, DRL, or advanced LED/HID systems). Always start with the owner's manual or the headlight diagram, verify the bulb base and rating, and follow proper safety procedures during replacement. When in doubt, consult a qualified technician to ensure correct fit, performance, and compliance with road-safety regulations.