Honda Fit (GK) Halogen-to-Projector Headlight Retrofit

Each headlight is held by four nuts: two along the top edge, one on the side, and one tucked behind the bumper alongside a retaining clip — release that clip carefully so it isn't lost or broken. After the fasteners are out, pop off the small plastic cover that sat over the side nut, then angle the headlight downward and slide it free rather than pulling it straight out, which reduces the chance of scuffing the lens. You also need to free the plastic trim that wraps the turn-signal area; its retaining bolt is located underneath the headlight.

Take out the four screws securing each housing. With those removed, work a flathead screwdriver under the perimeter clips and coax them partway open — they don't need to be fully released, just started, because they let go more easily once the housing is warmed. Also detach the H4 bulb retainer at the rear by removing its screw and lifting the clip away.

Soften the factory sealant so the clear lens lifts off the housing. In an oven, run 275-300 F for 10-15 minutes, adjusting for how hot your oven actually runs. If the housings are too large for your oven, a heat gun works but is slower: warm a section, then pry gently with a flathead you don't mind marking, easing the gray butyl free as you go along the channel. Work your way around and lift the lens once the glue gives. While everything is still warm, scrape as much leftover butyl out of the sealing groove as you can.

Look into the reflector bowl and locate the white plastic retainer that carries the vertical aim adjuster. Do not back that bolt out — doing so strips the plastic retainer, and pliers won't get it loose either. Instead, run the vertical aim adjustment so the bowl tilts upward and gives you working room; a further clip appears to anchor the bowl down the center toward the turn signal, but reaching it would mean drilling, which isn't worth it. Then find the two screws that also hold the bowl and simply loosen them rather than removing them. That opens enough clearance to reach in and take out the screw holding the halogen anti-glare shield, and remove the shield.

With the housing open you can customize the internals. Spray the reflector bowl any color you like, paint the turn-signal housing, or delete the amber reflectors. Let all paint fully dry and cure before reassembly so fumes and tackiness don't fog the lens later.

TRS-style retrofit projectors screw directly onto the reflector bowl, so this is mechanically simple but needs fitment work. Dry-fit the projector first. The mounting flange sits too tall for the H4 washer and hex nut to thread on, so grind the flange down with a rotary tool and then sand it flush with the washer. Also file down the centering nub on the H4 washer — the GK halogen bowl doesn't clear it, and leaving it prevents horizontal rotation of the projector. Skipping the nub leaves the beam with slanted, angled cutoff edges instead of a level line. (The nub issue was noted for the X-lens and may not apply to the O-lens.) Sand until the projector can rotate and the hex nut hand-tightens on the far side of the bowl; leave it snug, not fully torqued, for now.

Fit the HID bulbs, then set the still-open housings back onto the car and connect the wiring. Use a MotoControl Bi-xenon H4 harness — the Canbus H4 kit is the wrong one for this setup. A 35W ballast is a good default; 55W ballasts are brighter but shorten bulb life, whether you run true 55W bulbs or overdrive 35W ones. Power on the headlights and inspect the beam cutoff, rotating the projector until the horizontal line is dead level. Once it's right, tighten the hex nut, and lock the projector permanently with a dab of quick epoxy. Epoxy the shroud too if it fits loosely.

With the projector locked and the cutoff verified so it can no longer shift, pull the housings back off the car. Lay fresh butyl into the sealing channels, seat the lens back onto the housing, and reheat — oven or heat gun, whatever you used to open it — to bond the joint. After it cools and closes up, trim away any butyl that squeezed out of the seam.

Refit the sealed headlights to the car, reversing the removal steps and reattaching the turn-signal trim. Pull DRL fuse #25 so the factory daytime running function no longer drives the retrofitted lights, then power up and confirm operation.