How to Maintain, Repair, and Upgrade the Infiniti G37 Headlight: A Complete Guide for Owners

The Infiniti G37, a beloved sports coupe and sedan, is celebrated for its sleek design, powerful V6 engine, and driver-focused features. Yet one component that often gets overlooked—until it fails—is its headlight system. Functional headlights are critical for safety, visibility, and compliance with road laws, yet many G37 owners wait until darkness, flickering lights, or legal warnings prompt action. This guide cuts through the confusion: whether you’re dealing with a dim bulb, a cracked lens, or simply want to upgrade for better performance, we’ll walk you through everything you need to know about maintaining, repairing, and enhancing your G37’s headlights. By the end, you’ll have the knowledge to keep your lights shining bright, avoid costly repairs, and ensure your G37 looks and performs its best.

Why G37 Headlights Deserve Your Attention (and Regular Care)

Headlights on any vehicle degrade over time due to exposure to UV rays, road debris, temperature fluctuations, and general wear. For the G37, which debuted in 2007 and remained in production until 2013, older models may face accelerated aging if not cared for properly. The factory halogen bulbs (standard on most trims) have a lifespan of roughly 400–600 hours of use—meaning even with moderate driving, they’ll likely need replacement every 2–3 years. Meanwhile, the plastic headlight lenses can yellow, crack, or become hazy from UV damage, reducing light output by up to 50% over time. Poorly maintained headlights don’t just look bad; they reduce your ability to see the road at night, increase glare for oncoming drivers, and can lead to failed inspections or accidents. Proactive care isn’t just about convenience—it’s about safety and preserving your G37’s value.

Step 1: Routine Maintenance – Keep Your Headlights in Top Shape

Routine maintenance is the best way to extend the life of your G37’s headlights and avoid unexpected failures. Here’s what to do, and when:

1.1 Clean the Lenses Monthly

Road grime, bug splatter, and tree sap can accumulate on your headlights, blocking light and accelerating lens degradation. Start by rinsing the lenses with water to remove loose debris. Then, apply a dedicated headlight restoration cleaner (avoid household cleaners with ammonia, which can damage plastic). Scrub gently with a soft microfiber cloth or sponge, focusing on cloudy or yellowed areas. Rinse thoroughly and dry with a lint-free towel. For stubborn buildup, repeat the process or use a fine abrasive pad (like 2000-grit sandpaper) followed by a polish to restore clarity.

Pro Tip: Clean your headlights before they look dirty. Early intervention prevents deep-set stains and makes restoration easier.

1.2 Check Bulb Connections and Wiring Quarterly

Loose or corroded connections are a common cause of flickering or dim headlights. Open the hood and locate the headlight assembly (driverside and passengerside). Inspect the electrical connector attached to the bulb—look for frayed wires, rust, or corrosion. If you see buildup, disconnect the battery (to avoid short circuits), then use a wire brush or electrical contact cleaner to remove debris. Reconnect the plug firmly, ensuring it “clicks” into place.

1.3 Test Light Output Annually

Even if your headlights seem fine, their brightness may diminish over time. To test: park on a flat, dark surface (a garage or empty parking lot works) at night. Turn on the low beams and measure the distance the light reaches (use a measuring tape or estimate). Factory low beams should illuminate at least 200 feet ahead. If the light seems weak or uneven, it’s time to check the bulbs or lenses.

Step 2: Diagnosing Common G37 Headlight Problems – And How to Fix Them

Despite your best efforts, issues will arise. Here are the most common problems G37 owners face, along with actionable solutions:

2.1 “My Headlight Won’t Turn On”

Possible Causes:

• Burned-Out Bulb: The most frequent culprit. Halogen bulbs have a thin tungsten filament that can break due to vibration or age.
• Faulty Fuse: A blown fuse cuts power to the headlights.
• Bad Relay: The headlight relay (a small electronic switch) can fail, preventing current from reaching the bulbs.
• Damaged Wiring: Corrosion, fraying, or a loose connection in the wiring harness can interrupt power.

How to Diagnose:

1. Check the Fuse: Locate the headlight fuse in your G37’s fuse box (consult the owner’s manual for exact location—typically under the hood or in the cabin). Use a fuse puller or tweezers to remove the fuse and inspect the metal strip inside. If it’s broken, replace it with a fuse of the same amperage.
2. Test the Bulb: Remove the suspect bulb (see Section 3 for removal steps) and inspect the filament. If it’s broken or blackened, replace it. To test further, swap the bulb with the working one on the other side—if the non-working side now works, the bulb was the issue.
3. Check the Relay: Swap the headlight relay with a similar-rated relay in the fuse box (e.g., horn or AC relay, if labeled). If the headlights work after swapping, the original relay is faulty.
4. Inspect Wiring: Use a multimeter to test for voltage at the bulb socket when the headlights are on. If there’s no voltage, trace the wiring back toward the relay or fuse box for breaks or corrosion.

2.2 “My Headlights Are Dim or Flickery”

Possible Causes:

• Aging Bulbs: Halogen bulbs lose brightness as the filament wears down.
• Dirty Lenses: As discussed earlier, haze or yellowing blocks light output.
• Low Voltage: A failing alternator or battery can reduce the electrical system’s output, dimming all lights.
• Worn-Out Socket Contacts: Over time, the metal contacts in the bulb socket can corrode, reducing conductivity.

How to Diagnose:

1. Replace the Bulb: Even if it’s not completely burned out, a dim bulb is a sign it’s near the end of its life. Install a new halogen bulb (OEM or high-quality aftermarket) and test.
2. Clean Lenses: Follow the cleaning steps in Section 1.1. If the problem persists, the issue is electrical.
3. Test the Battery/Alternator: Use a multimeter to check the battery voltage (should be ~12.6V when off, ~13.8–14.8V when running). A reading below 12.4V indicates a weak battery; irregular voltage points to a failing alternator.
4. Inspect Socket Contacts: Remove the bulb and examine the socket for corrosion (white/green buildup). Clean with electrical contact cleaner and a cotton swab. Apply dielectric grease to prevent future corrosion.

2.3 “My Headlights Are Shining Too High or Low (Uneven)”

Possible Causes:

• Misaligned Beam Pattern: The headlight aim can shift due to potholes, rough roads, or improper installation of aftermarket parts.
• Damaged Reflector: The internal reflector (behind the bulb) can warp if the bulb overheats (e.g., from using a higher-wattage bulb than recommended).
• Cracked Lens: A cracked lens can distort light output.

How to Diagnose:

1. Check Alignment: Park on a flat surface 25 feet from a wall. Turn on low beams and measure the height of the light beam relative to the ground. The top of the low beam should hit the wall 2–4 inches below the headlight’s center height. Adjust using the headlight adjustment screws (located on the headlight assembly—consult your manual for torque specs).
2. Inspect Reflector: Remove the headlight assembly and shine a flashlight into the back of the reflector. If the surface is warped or pitted, the reflector needs replacement.
3. Examine the Lens: Look for cracks or discoloration. Minor cracks can be repaired with plastic epoxy, but severe damage requires lens replacement.

Step 3: Replacing G37 Headlight Bulbs – A Step-by-Step Guide

Replacing a G37 headlight bulb is a simple DIY task, but it requires care to avoid damaging the bulb or electrical system. Here’s how to do it:

Tools You’ll Need:

• Replacement halogen bulb (check your owner’s manual for the correct part number—for 2008–2013 G37s, the low beam is typically a 9006/HB4, high beam is H13)
• Latex or nitrile gloves (to prevent oils from your hands from coating the bulb)
• Small flathead screwdriver (to pry open the headlight housing clips)

Step-by-Step Instructions:

1. Turn Off the Vehicle and Let It Cool: Headlights generate heat—even after turning them off, the bulbs can stay hot for 10–15 minutes. Wait to avoid burns.
2. Open the Hood and Access the Headlight Assembly: The headlight assemblies are located on either side of the front bumper. Remove the two plastic clips holding the top of the assembly in place (use a flathead screwdriver to gently pry them up). Then, unclip the bottom two tabs (some models may have screws—check your manual). Pull the assembly straight out toward the front of the car.
3. Disconnect the Electrical Connector: Twist the connector counterclockwise to unlock it, then pull it straight off the bulb.
4. Remove the Old Bulb: Gently twist the bulb counterclockwise (usually ¼ turn) and pull it out of the socket. Avoid touching the glass part of the new bulb with your bare hands—oils can cause hot spots, reducing lifespan.
5. Install the New Bulb: Handle the new bulb by its plastic base. Insert it into the socket and twist clockwise until it clicks into place.
6. Reconnect the Electrical Connector: Align the connector with the bulb socket and twist clockwise to lock it.
7. Reinstall the Headlight Assembly: Line up the clips and tabs, then push the assembly back into place until it clicks. Replace any screws or clips you removed.
8. Test the Lights: Turn on the headlights to confirm the new bulb works. Adjust the aim if necessary (see Section 2.3).

Step 4: Upgrading Your G37 Headlights – From Halogen to HID or LED

While the factory halogen system is functional, upgrading to HID (High-Intensity Discharge) or LED (Light-Emitting Diode) bulbs can drastically improve brightness, beam pattern, and style. Here’s what you need to know before upgrading:

4.1 HID Upgrades

HID bulbs produce light by ionizing xenon gas, resulting in a brighter, whiter light (5,000–6,000K color temperature) compared to halogens (3,200K). They also last longer (2,000–3,000 hours) and consume less energy.

Pros:

• Brighter, more focused beam pattern.
• Modern, sporty look.
• Longer lifespan than halogens.

Cons:

• Higher upfront cost ($100–$300 per kit).
• Requires a ballast and igniter (included in most kits).
• Some HID bulbs may cause glare if not aimed properly.

Important Notes:

• Ensure the HID kit is designed specifically for the G37’s headlight housing. Poorly designed kits can cause light spill or reduce beam focus.
• Check local laws—some regions restrict HID use in halogen housings due to glare concerns.

4.2 LED Upgrades

LED bulbs use semiconductors to emit light, offering instant full brightness, lower power draw, and even longer lifespans (30,000–50,000 hours). They’re available in a range of color temperatures (4,300K–6,500K) and often include built-in drivers to mimic halogen electrical requirements.

Pros:

• Energy-efficient (uses ~30% less power than halogens).
• No warm-up time—bright from the moment they’re on.
• Compact size fits most G37 housings.

Cons:

• Lower-quality LEDs may produce uneven beam patterns or excessive glare.
• Higher-end LEDs can cost $150–$400 per pair.

Important Notes:

• Choose LED bulbs with a “canbus-compatible” design to avoid error messages on your dashboard (common in newer vehicles, but still relevant for G37s with upgraded electrical systems).
• Prioritize bulbs with a “projector-compatible” label if your G37 has projector-style headlights (2008+ models). These projectors focus light better than reflector-style housings, reducing glare.

4.3 Legal and Safety Considerations

Before upgrading, check your state or country’s regulations. Most areas require headlights to emit a white or amber light (no pure blue or red) and limit maximum brightness to avoid dazzling other drivers. For example, in the U.S., SAE (Society of Automotive Engineers) standards prohibit aftermarket bulbs that exceed 4,300K color temperature in halogen housings without additional shielding. Always choose reputable brands (e.g., Philips, Sylvania, Morimoto) that test their products for compliance.

Final Thoughts: Protect Your Investment and Stay Safe

Your Infiniti G37’s headlights are more than just accessories—they’re a critical safety feature and a key part of its functionality. By following this guide, you’ll be equipped to maintain your lights, diagnose common issues, perform DIY repairs, and even upgrade for better performance. Remember: regular checks and proactive care will save you money in the long run, keep you safer on the road, and ensure your G37 looks as sharp as it drives. Whether you’re a weekend DIYer or prefer professional help, prioritizing your headlights is one of the smartest investments you can make in your vehicle.