Turn signals are one of your most important exterior lights. If one is burned out, other drivers may not know when or if you are turning. The 2004 to 2009 Volvo S40's turn-signal bulbs aren't difficult to replace; however, they are stored within the headlight housing; replacing one requires removing the housing from the S40. If your Volvo S40 is equipped with Bi-Xenon headlights, do not attempt to remove the headlight housing. With Bi-Xenon lights, professional replacement is required; the system is extremely high voltage.
Turn your headlight switch to position "0," and then turn the engine off. Put on a pair of gloves to prevent damage to the bulb. Pull up the retaining pin at the rear of the headlight housing. Use pliers if you can't pull it up with your hands.
Pull the inner corner of the headlight housing out first, and then pull the entire unit out. Unplug the adapter on the back. This fully separates the housing from the S40. Bring it to a suitable work table and set it down.
Turn the headlight over to expose its rear. On the back you'll find the bulb cover. Push the pins on the sides outward to release the cover; then pull it off.
Unscrew the bulb holder and pull it out of the housing. The turn-signal bulb is the far-outside bulb. Push the bulb into the bulb holder; while applying pressure, twist it counterclockwise to remove it.
Insert the new bulb into the bulb holder; push it down gently. Re-insert the bulb holder; twist it clockwise. Replace the large bulb cover. Push the two pins inward to secure it.
Reconnect the adapter to the rear of the headlight housing. Re-insert the headlight housing; insert the outboard corner first, and then push in the inner corner. When it's in place, push down the retaining pin to secure it.
