2015 Subaru Forester Bulb Size Guide

Whether you're dealing with a burnt-out bulb or planning a performance lighting upgrade, knowing the correct bulb sizes for your 2015 Subaru Forester is the first step. This guide provides a comprehensive list of bulb sizes, replacement tips, and common issues to help you get the job done right.

Quick Reference Bulb Size Chart

This chart covers the most common bulb sizes for the 2015 Subaru Forester across its various trim levels (2.5i, 2.5i Premium, 2.5i Limited, 2.5i Touring, 2.0XT Premium, and 2.0XT Touring). Always double-check your owner's manual or the existing bulb, as variations can occur.

LED vs. Halogen Upgrade Considerations

Upgrading your Forester's stock halogen bulbs to LEDs can provide a significant improvement in brightness, visibility, and lifespan. However, there are a few key things to consider before making the switch.

• CANBUS Errors: Subaru vehicles of this era use a CANBUS (Controller Area Network) system to monitor the vehicle's electronics, including the lighting. Since LEDs draw much less power than halogen bulbs, the system can mistakenly think a bulb is burnt out. This will trigger a "bulb out" warning light on your dash. For turn signals, it results in "hyperflash" (the signal blinking very rapidly).
• Resolving Errors: To prevent these issues, you need to use "CANBUS-ready" or "Error-Free" LED bulbs, which have built-in resistors to mimic the power draw of a halogen bulb. Alternatively, you can wire an external load resistor in parallel with the turn signal or DRL wiring. Be aware that these resistors get very hot and must be mounted to a metal surface away from plastic or other wiring.
• Adapters and Fitment: While most LED bulbs are designed to be plug-and-play, the larger heat sinks on some high-power headlight bulbs can sometimes interfere with the dust cover. For the H11 low beams, ensure the replacement LED has a collar that installs separately, allowing you to clip it into the housing before inserting and twisting the bulb.

How to Replace Each Bulb

Here are some quick tips for accessing the most commonly replaced bulbs on your 2015 Forester.

• Low & High Beam Headlights: These are accessible from under the hood. Simply locate the back of the headlight housing, twist the bulb's wiring harness counter-clockwise, and pull it out. The bulb can then be unclipped from the harness. Avoid touching the glass of new halogen bulbs with your bare hands, as skin oils can cause them to fail prematurely.
• Fog Lights: Access is typically gained from underneath the front bumper. You may need to remove a few plastic push-clips from the splash shield to reach up and twist out the bulb housing.
• Tail & Brake Lights: Open the rear hatch. On the side of the cargo area, you'll see a plastic panel. Pop it open to reveal two 10mm bolts holding the tail light assembly in place. Remove these bolts, and the entire assembly will pull straight back out of the vehicle body. Twist the appropriate bulb socket to remove it.
• Front Turn Signals: Like the headlights, these are reached from under the hood. It's the large amber bulb socket in the headlight housing.
• License Plate Lights: Look for the small plastic housings above the license plate. You can usually use a small flathead screwdriver, wrapped in tape to prevent scratching, to gently pry the lens housing out. Twist the socket and replace the bulb.
• Interior Dome/Map Lights: A plastic trim removal tool is your best friend here. Carefully pry off the clear plastic lens to expose the bulbs. The map lights are wedge-style bulbs you can pull straight out, while the central dome light is a festoon bulb held in by metal clips.

Common Lighting Issues for this Generation Forester

The 2014-2018 Forester generation is generally reliable, but a few common lighting-related quirks can appear.

• Daytime Running Light (DRL) Failure: The DRLs are the high beam bulbs (9005) running at a lower voltage, controlled by a resistor. This resistor can sometimes fail, causing the DRLs to stop working while the high beams still function normally. The resistor is located near the driver's side strut tower in the engine bay.
• Premature Halogen Burnout: Some owners report a shorter-than-expected lifespan from the stock H11 low-beam halogen bulbs. This can be due to vibrations, voltage irregularities, or touching the bulb during installation. Switching to a quality long-life halogen or a reputable LED kit can be a permanent solution.
• HID Ballast Failure: For Touring models equipped with factory HID headlights, the ballast (the small metal box that powers the HID bulb) can fail over time. Symptoms include flickering headlights or a light that refuses to turn on. Replacing a ballast can be expensive and involves high-voltage components, so it's often best left to a professional.

If you encounter any of these issues or simply don't feel comfortable performing the work yourself, professional help is always a great option.

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