The tail light bulb in a 2018 Subaru Forester is typically a 3157 dual-filament bulb.
However, exact part numbers can vary by market, trim level, and whether the vehicle uses a shared tail/brake/turn bulb or separate bulbs for each function. To ensure you buy the correct part, consult your owner’s manual, inspect the bulb socket, or check Subaru’s official parts diagrams for your VIN and region.
Understanding the tail light setup on the 2018 Forester
Rear tail lights on this generation are part of a rear combination lamp that can include tail/running, brake, turn, and reverse functions. The most common replacement bulb in the tail/stop function is from the 3157 family, but there are regional variations and suffixes that can appear on part listings. Verifying the exact bulb by inspecting the socket or the paperwork that came with your car helps prevent ordering the wrong part.
Before you replace, it helps to know how to identify the correct bulb in your specific vehicle. The steps below guide you through verifying the exact bulb size and part number for your Forester. The list is designed to help you confirm the proper bulb before purchasing or handling the wiring side of the replacement.
Identify and verify the correct bulb using these steps:
- Open the trunk and locate the rear tail light assembly on the exterior of the vehicle.
- Access the bulb socket by removing the inner trim panel or rubber boot as needed, then twist the socket counterclockwise to remove it.
- Carefully pull out the bulb and read any numbers printed on the bulb base or glass; compare these markings to a trusted parts diagram for your VIN.
- Cross-check the markings with Subaru’s official parts catalog or a reputable retailer to confirm the exact part number (for example, entries in the 3157 family or any local suffix such as 3157NA or 3157A).
Common variations you may encounter come from regional differences and trim-specific setups. Some markets may use the standard 3157 family for the tail/brake/turn function, while others might use a separate bulb for the reverse light or a slightly different suffix. If in doubt, rely on the official diagram for your vehicle’s VIN to avoid ordering an incompatible bulb.
Replacing the bulb and choosing a replacement
Once you’ve confirmed the exact bulb size, you can proceed with replacement. The process is typically straightforward, but if you’re not comfortable working with vehicle electrics, a professional technician can perform the swap quickly.
- Purchase the confirmed bulb type from a dealer, Subaru Genuine Parts, or a trusted aftermarket supplier, ensuring it matches the exact size and fit for your vehicle.
- When replacing, handle bulbs with clean gloves or a cloth to avoid transferring oils from your skin to the glass, which can reduce bulb life.
- Test all rear lighting functions after installation (tail lights, brake lights, and turn signals) to ensure proper operation and to avoid a burnt-out condition that could trigger warning lights.
Note: If you’re considering LED replacements for the tail light, verify compatibility with your vehicle’s electrical system and check for any required resistors or load electronics to prevent issues such as rapid flashing or dashboard warnings.
Summary
For a 2018 Subaru Forester, the tail light bulb is commonly a 3157 dual-filament type, but exact part numbers can vary by market and trim. Always verify by consulting the owner’s manual, inspecting the bulb markings, or checking Subaru’s official parts diagrams for your VIN. This helps ensure you purchase the correct bulb and maintain proper function of the tail, brake, and turn signals.