The brake light bulb is typically a dual-filament 12-volt bulb, usually giving both tail and brake illumination. In practice, you’ll commonly need a P21/5W bulb (the US equivalent is often listed as 1157). However, the exact bulb type can vary by model year and market, so you should verify by checking the current bulb or the owner’s manual.
Common bulbs by Fiesta generation
Fiesta models across different markets have used a few standard dual-filament bulbs for the brake/taillight assembly. The base and marking can differ by year and region; the following are the most frequently encountered possibilities.
- P21/5W dual-filament bulb (often with a bayonet base; US buyers may see it listed as 1157).
- W21/5W or W21W wedge-base dual-filament bulb (used on some European-market Fiests).
The exact bulb can vary, so check the bulb currently installed or your manual to confirm the base type and wattage. If you’re unsure, bring the old bulb to a parts store or look up your exact year/market and trim online for a precise match.
How to identify and replace
Use this step-by-step guide to locate, identify and replace the brake light bulb safely.
- Confirm the correct bulb type by removing the brake light bulb and reading the markings on the glass (for example, P21/5W or W21/5W) and noting the base type.
- Gather tools and materials: a new bulb, gloves or a cloth to handle the bulb, and a clean workspace.
- Open the trunk and access the brake light housing by removing any trim, shelf, or lining as needed.
- Remove the light cluster cover or socket by twisting or unclipping, depending on your model.
- Carefully release the old bulb from the socket and unplug any wiring harness if required.
- Install the new bulb in the same orientation, reassemble the housing, and test the brake light to ensure proper operation.
Avoid touching the glass of the new bulb with bare hands; oils can shorten bulb life. Wear gloves or handle with a cloth.
Where to buy and compatibility tips
To ensure compatibility, note your car’s year, market (EU/US), and, if possible, the old bulb code when shopping for a replacement. Bulbs are available at automotive parts stores, retailers, and online. If you’re uncertain, a parts professional can verify the correct P21/5W or W21/5W replacement for your Fiesta.
As a general practice, replace in pairs when one brake light is out to ensure equal brightness and signaling. After replacement, test all lights and check the fuses if needed.
Summary
In most Ford Fiesta models, the brake light uses a dual-filament 12-volt bulb—commonly P21/5W (US equivalent 1157). Exact base and code can vary by year and market, so confirm by inspecting the current bulb or consulting the manual. When in doubt, seek guidance from a parts specialist to ensure you get the right dual-filament bulb for your specific Fiesta.