Buy Lexus RX300 Headlight Assembly

Background Info

The Lexus RX300 headlight-also called a headlamp, front light, or lamp assembly-is the main safety light at the nose of every 1999-2003 RX300. It fits either halogen bulbs or factory-option HID (High-Intensity Discharge) bulbs, and owners often deal with bulb changes, moisture in the lens, cloudy plastic, or aiming issues. Keeping the light sealed, clear, and aimed protects night vision and meets U.S. road rules such as FMVSS 108.

Fit & Years

• Model years: 1999, 2000, 2001, 2002, 2003. All share the same housing shape.
• Halogen vs. HID: Most RX300s shipped with halogen. HID lamps were bundled with the navigation package starting in 2001, and those housings include auto-leveling hardware. (Lexus Owners Club of North America, Lexus Owners Club of North America)
• Left & right: Buy the side that matches your VIN; they are not interchangeable because of aim and mounting tabs. (Internal Lexus service manuals separate part numbers by side.)

Bulb Types

Below are the factory bulb sizes (always confirm on your vehicle sticker before ordering):

• Low beam: 9006 (HB4) halogen or D2R HID (navigation package).
• High beam / DRL: 9005 (HB3).
• Fog lamp: 9006 (HB4).
• Turn/stop: 7440/7443.
• License & interior: T10/194.

Common Problems

• Condensation or water beads inside the lens are common on first-generation RX300 lights. They trace to worn rubber seals or minor housing cracks.
• Lexus later extended warranty coverage on newer RX models for "excess headlamp moisture," showing the maker acknowledges the concern.
• Yellow or cloudy plastic comes from UV-damaged polycarbonate, which cuts light output.
• Flicker or intermittent shut-off can come from a weak alternator, loose grounds, or a failing HID ballast.
• Aim too low/high after suspension work? The RX300 has manual vertical screws and, on HID units, a rear-axle height sensor that must sit level.

Maintenance Tips

• Seal checks: Inspect the black rubber gasket around the lens every oil change; replace if brittle.
• Clean & polish: AAA recommends washing, wet-sanding with 1000-2500-grit, then applying plastic polish and a UV sealant to clear haze.
• Moisture fix: Remove bulbs, vacuum the housing gently in a warm garage to evaporate trapped water, then reseal leaks with automotive-grade silicone.
• Electrical care: Keep battery and alternator healthy; low voltage accelerates bulb failure and ballast stress.

DIY Installation

Tools: 10 mm socket, Phillips screwdriver, painter's tape, gloves.

1. Remove the front wheel nearest the headlight.
2. Peel back three fender-liner screws to expose two 10 mm nuts on the lamp's outer edge.
3. Undo the third 10 mm nut at the grille.
4. Slide the housing forward; unplug the multi-pin connector and bulb sockets.
5. Reverse steps to install the new lamp, then aim on a level wall 25 feet away.

Legal & Safety

• U.S. rule FMVSS 108 says each headlight must include amber side reflectors and meet brightness limits to avoid glare. Non-compliant aftermarket lamps can be recalled.
• Check alignment: Low-beam cutoff should hit about 2 in. below lamp height at 25 ft. Upward aim can dazzle traffic and earn a ticket.
• When upgrading to brighter LED or HID bulbs, confirm DOT compliance and proper beam focus to stay legal. A 2400-lumen LED retrofit offers more light but may not be street-approved if marked "off-road only."

Upgrade Ideas

• LED retrofit kits give whiter light and draw less power; choose kits with in-base cooling fans and adjustable collars so the diode sits at the same focal point as the halogen filament.
• Projector swaps: Enthusiasts retrofit HID projectors from later Lexus models for sharper cut-off. The HID housing uses a different reflector than halogen, so swapping whole units is easier than mixing parts.
• Clear-lens replacements: Aftermarket "crystal" housings refresh the look but verify they keep OEM-style beam patterns and have DOT markings.

Related Systems

• Daytime Running Lights (DRL): On RX300, the high-beam filament runs at reduced voltage for DRL. Frequent on-off cycles shorten bulb life; an LED high-beam can reduce heat and last longer.
• Auto-leveling (HID only): A suspension sensor tilts HID lamps when the rear is loaded. If the sensor arm bends, the beam will point at the road or sky.

Frequently Asked Questions

Q: What headlight bulb does a 2000 RX300 use?
A: Low beam is 9006 (HB4) halogen; high beam is 9005 (HB3). HID-equipped models use a D2R capsule for the low beam.

Q: Why is moisture inside my light?
A: A worn seal or hairline crack lets humid air in. Heating and cooling cause condensation on the lens. Replace seals or the housing to stop repeats.

Q: Can I just swap in an HID bulb without changing the housing?
A: No. HID bulbs need a dedicated reflector/projector and a ballast. Mixing parts can scatter light and violate FMVSS 108.

Q: How bright are LED retrofit bulbs?
A: Quality kits put out roughly 2,400 lumens per bulb-about twice a stock halogen-but only if they stay in focus and have proper cooling.

Q: My lights flicker; is it the bulb or ballast?
A: Swap the suspect bulb to the other side. If the problem moves, it's the bulb; if not, test or replace the ballast and check wiring grounds.

Q: How do I aim the headlights?
A: Park 25 ft. from a wall on level ground, find the vertical and horizontal adjuster screws, and set the low-beam cut-off about 2 in. below and slightly right of lens height.

Q: Do cloudy lenses fail inspection?
A: Many states require headlights to project 100-150 ft. at low beam. Heavy haze can cause rejection; cleaning kits or replacement housings restore clarity.

Q: Is there a recall for RX300 headlights?
A: No recall exists for 1999-2003 RX300, but Lexus issued a moisture-warranty extension on 2004-2009 RX models, showing similar concerns.

Q: What tools do I need to remove the lamp?
A: A 10 mm socket, Phillips driver, and trim fastener tool. Removing the wheel and fender liner gives clear access to the three mounting nuts.

Q: Can I prevent yellowing after restoration?
A: Yes-apply a UV-blocking clear coat or film after polishing. Park in the shade when possible and wash lenses regularly.

Q: Are side reflectors required?
A: Yes. FMVSS 108 mandates amber side reflectors on front combination lamps for lateral visibility; aftermarket lights must include them.