🔧 550i - Taillight Bulb Replacement

On your 550i, most rear light functions are LED and don’t use replaceable “bulbs.” The commonly serviceable bulbs are usually the reverse (backup) light bulbs in the trunk-lid lamp areas—those can be replaced from inside the trunk.

Assumption: You’re replacing the left + right serviceable rear bulbs (most often the reverse/backup bulbs). If your “taillight/brake/turn” is out and it’s LED, the fix is typically a lamp assembly, not a bulb.

Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours

---

⚠️ Safety & Precautions

• ⚠️ Turn the ignition fully OFF and remove the key/fob from the car.
• ⚠️ Let bulbs cool before touching them; they can be hot.
• ⚠️ Wear gloves to keep oils off the glass (helps bulb life).
• ⚠️ Support the trunk lid securely; don’t lean hard on trim panels.

---

🔧 Required Tools

You'll need the following tools for this repair:

• Plastic trim removal tool set
• Torx T20 driver
• Small flat-blade screwdriver
• Flashlight
• Nitrile gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Reverse/backup light bulb - Match type to old bulb (commonly W16W/921) - Qty: 2

---

📋 Before You Begin

• Park on level ground and set the parking brake.
• Open the trunk and remove any luggage so you can work comfortably.
• Have your flashlight ready—access holes can be hard to see.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Access the trunk-lid lamp area

• Open the trunk.
• Use a flashlight to locate the access area in the trunk-lid inner trim (the trim panel attached to the trunk lid).
• If there’s a small cover, remove it using a plastic trim removal tool set (a plastic pry tool that pops clips without scratching).

Step 2: Remove the trunk-lid inner trim (if needed)

• If you can’t reach the bulb socket through an access cover, you’ll need to loosen/remove the trunk-lid liner.
• Use a Torx T20 driver to remove any visible Torx screws.
• Use a plastic trim removal tool set to pop the plastic clips free around the edge.
• Tip: Pull straight down; don’t twist the panel.

Step 3: Remove the bulb socket

• Find the bulb socket going into the trunk-lid tail lamp (follow the wiring to the back of the lamp).
• Grip the socket and rotate it counterclockwise by hand.
• If it’s tight, use a small flat-blade screwdriver gently on the socket tabs to help it start turning (don’t crack the plastic).

Step 4: Replace the bulb

• Pull the old bulb straight out of the socket using nitrile gloves.
• Install the new bulb by pushing it straight in until fully seated.
• Match the bulb type by comparing the new bulb to the old one (same size and contact style).

Step 5: Reinstall the socket and test

• Reinsert the socket into the lamp and rotate clockwise until it locks.
• Turn the ignition ON and test the light (reverse lights require the car to be in reverse; use a helper and keep your foot on the brake).
• Tip: If it doesn’t work, flip-check seating and socket lock.

Step 6: Reinstall trim

• Reposition the trunk-lid liner and press the clips back in by hand.
• Reinstall any screws using a Torx T20 driver until snug.
• Snap the access cover back into place using a plastic trim removal tool set.

---

✅ After Repair

• Verify both left and right bulbs illuminate correctly.
• If you still get a bulb warning, recheck the socket lock and bulb seating.
• If the failed light is an LED function (tail/brake/turn), the repair is usually replacing the lamp assembly rather than a bulb.

---

💰 DIY vs Shop Cost

Shop Cost: $100-$220 (parts + labor)

DIY Cost: $10-$40 (parts only)

You Save: $60-$210 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 hours.

---

🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.