Owners of other Ford or Lincoln vehicle such as the Explorer, Fiesta, Focus, Fusion, C-Max, Mustang, Taurus, EcoSport, Escape, Edge, Expedition, Transit Connect, F-150, Ranger, MKZ, MKC, Navigator, MKX and Continental may also find these DIY instructions to be helpful.

If your Flex is equipped with Xenon HID (high intensity discharge) low / high beam headlight bulbs, the compatible replacement part number is D3S.

If your Flex has standard halogen low / high beam headlight bulbs, the replacement part number is H13.

The other compatible replacement light bulb part numbers are as follows: Front Turn Signals 3157NA (or 3457NA) and Front Side Marker 168. (Most model years are equipped with LED front side marker lights.)

The tools needed to access and replace the Xeon HID headlight bulbs include a 5.5mm socket with a 1/4" drive ratchet and a Torx T10 star bit screwdriver.

No tools are needed to access and replace the standard halogen headlight bulbs. Just pull off the rubber dust cap or twist off the plastic dust cover, rotate the old bulb 1/4 turn in the counterclockwise direction and disconnect the power plug.

The ballasts for Xenon HID bulbs operate at a very high voltage which can be dangerous.

Disconnecting the negative terminal on the 12V battery and allowing some time to pass will ensure that the capacitor in the bulb ballast is no longer energized. The ballasts usually have a bleed resistor to safely dissipate the stored electricity when the power is disconnected.

Disconnecting the battery is also a good idea to prevent the possibility of someone accidentally turning on the headlights while you are replacing the bulbs.

Remove the "-" negative terminal by turning the nut in the counterclockwise direction with a 10mm socket and a 1/4" drive ratchet.

Pull off the negative terminal from the "-" battery post, wrap it in a small towel and tuck it away on the side of the battery to help prevent accidental electrical contact.

If the old light bulb was recently turned on, allow some time for it to cool off.

There is a plastic dust cover on the back side of the low / high beam headlight housing.

It is held in place by four small Torx T10 screws.

Three of the screws can be accessed from inside the engine bay. The fourth screw can only be accessed by going in through the wheel well.

Locate the black plastic pop rivet and three black metal screws on the wheel well liner.

Pry out the center of the pop rivet fastener with a flathead screwdriver to unlock it.

Then pry out the base of the pop rivet. Set it aside in a safe place.

Set the three screws aside in a safe place.

Carefully spin out the screws the last turn or two by hand to prevent from loosing them.

Pull back the wheel well liner.

Remove the fourth Torx T10 screw by turning it in the counterclockwise direction.

Carefully pull the dust cap off the rear of the headlight assembly.

Once the cover is out of the way, you'll be able to see the ballast on the rear of the old Xenon HID bulb.

I recommend wearing rubber gloves for the next few steps for extra safety.

Locate the orange plastic electrical connector on the bottom of the old bulb assembly.

Carefully rotate the base of the old light bulb 1/4 turn in the counterclockwise direction before pulling it straight out of the socket.

Avoid touching the glass part of the new Xenon HID bulb with your fingers or anything greasy in the engine bay.

Install the new D3S bulb into the housing and rotate it 1/4 turn in the clockwise direction to secure it into place.

Push the electrical connector straight into the socket on the bottom of the ballast.

You should hear or feel the power plug "click" securely into place.

Push the dust cover back into place on the rear of the headlight housing.

Replace the fourth screw from the wheel well.

Re-insert the black plastic pop rivet and push in the center piece to secure it into place.

If you have an early model year Flex with a traditional incandescent front side marker light, the compatible replacement miniature wedge base light bulb part number is 168.

It might be easiest to access the side marker bulb socket through the wheel well liner.

The two turn signal lights are located near the inner edge of the housing.

Locate the grey and black plastic bulb sockets from the top of the engine bay.

Gently pull the old turn signal light bulb straight out of the socket.

You may need to slightly wiggle the old bulb while pulling it out.

Push a new number 3157NA or 3157A bulb straight into the socket.

(Sylvania specifies that their 3457A bulb is also compatible with the 2009 to 2019 Flex.)

Re-insert the bulb socket into the housing and rotate it 1/4 turn in the clockwise direction.

Repeat the steps for the second front turn signal light bulb if necessary.

Try to avoid over tightening the terminal nut to prevent from cracking the battery post which could lead to an acid leak.

To test the new light bulbs, turn on the headlights, flash the high beams and activate the hazard signals.

Be sure to record the bulb change in your SUV's service records.

If you disconnected the 12 volt battery, please remember to adjust the time on the clock and program your favorite radio stations before you begin driving.

Please check out all of my Ford Flex DIY Repair & Maintenance Guides.