The 2003 Mazda 6 sedan uses four identical H1 halogen bulbs for its high and low beam headlights. The manufacturer recommends the headlights only be serviced by an authorised dealer, but you can replace the bulbs yourself with no tools required. The process is made more challenging because the area around the headlight housing is very cramped, so be sure to allow yourself plenty of time to get the job done right.
Identify the bulb that has burnt out. The high and low beam bulbs are housed in the same assembly. The low beam bulb is located on the outside edge of the housing while the high beam bulb is on the inside edge.
Turn the headlights off and remove the keys from the ignition. For safety, disconnect the negative terminal of the car battery to shut off the flow of electricity to the light. Release the hood latch and raise the hood.
Locate the headlight assembly. Remove the plastic cover labelled "Top" from the rear of the housing and set aside. The base of the high and low beam bulbs will be exposed.
Remove the power supply wire connected to the bulb by pulling it straight out. The bulb is held in place by a wire clip, press on the tab to release it. Carefully note the position of the bulb, the round base should have a single flat edge facing upwards. Remove the bulb.
You may want to practice the installation process with your old bulb before you insert the new one. Scratching the glass surface of the new bulb during installation could damage it.
Put on latex gloves, or nitrile gloves if you are allergic to latex. Never touch the glass element of the halogen bulb with your bare hands. Remove the new H1 bulb from its packaging.
Insert the new bulb into the housing, again with the flat edge of the base facing upwards. Replace the wire clip by pressing until it locks into place. Attach the power supply wire to the exposed end of the bulb.
Test the bulb by turning the headlights on. Replace the assembly cover by turning it until the word "Top" is visible. Dispose of the old bulb by placing it in the new bulb's package and tossing in your household trash.
If you have difficulty seeing the rear of the headlight housing due to the cramped space, a small mirror may help you get a better view of the assembly.
Halogen headlamp bulbs are pressurised and will explode if dropped. Never touch the glass portion of a halogen headlamp. The oils on your skin could cause the bulb to overheat and will shorten the life of the bulb.