2021 Nissan Altima Bulb Sizes (Headlight, Tail, Fog)

Quick reference

The 2021 Nissan Altima offers a mix of halogen and LED lighting, depending on the trim level and optional packages. Understanding these differences is crucial when considering bulb replacements or upgrades.

Headlights

Low Beam: On Altima models equipped with halogen headlights, the low beam utilizes an H11 bulb. Higher trim levels, such as the SL and Platinum, often come with integrated LED low beams from the factory. These LED units are not designed for bulb replacement; if they fail, the entire headlight assembly typically needs to be replaced.

High Beam: Similarly, halogen-equipped Altimas use an H9 bulb for the high beams. Altimas with factory LED low beams also typically feature integrated LED high beams.

Fog Lights: The fog lights on all 2021 Nissan Altima trims, when present, use an H11 bulb. This is a common halogen bulb size, making upgrades relatively straightforward.

Daytime Running Lights (DRL): For models with halogen headlights, the DRLs commonly use a 2825 halogen wedge bulb. Altimas with integrated LED headlights will have integrated LED DRLs that are not individually replaceable.

Exterior Signals and Lighting

Front Turn Signal: The front turn signals are typically 7440NA (amber) halogen wedge bulbs. The "NA" denotes natural amber, which is important for proper light color output.

Rear Turn Signal: The rear turn signals generally use a 7440 halogen wedge bulb.

Brake Light: The brake lights utilize a 7443 halogen dual-filament bulb. This bulb serves both the brake and tail light functions, with one filament for each.

Tail Light: As mentioned above, the tail lights also use a 7443 halogen dual-filament bulb.

Reverse Light: The reverse lights typically use a 921 halogen wedge bulb.

License Plate Lights: The license plate lights are powered by 168 halogen wedge bulbs.

Side Marker Lights: Both front and rear side marker lights commonly use 168 halogen wedge bulbs.

Interior Lighting

Dome Light: The dome light (center overhead light) usually takes a 31MM festoon-style bulb. It is often referred to as a "fuse" type due to its cylindrical shape.

Map Lights: The map lights (individual reading lights) typically use 168 halogen wedge bulbs.

LED vs Halogen Upgrade Considerations

Upgrading your 2021 Nissan Altima's halogen bulbs to LED can offer significant improvements in brightness, longevity, and a more modern aesthetic. However, there are several factors to consider:

• CANBUS Errors: Modern vehicles like the Altima use a Controller Area Network Bus (CANBUS) system to monitor electrical components. LED bulbs draw less power than halogens, which can sometimes trigger "bulb out" warnings or hyper-flashing (fast blinking) for turn signals because the CANBUS system interprets the lower draw as a burned-out bulb. To prevent this, you may need "CANBUS-compatible" LED bulbs or load resistors (decoders) wired into the circuit.
• Adapters: For some LED headlight and fog light conversions, you might need specific adapters or retainers to properly secure the new LED bulbs in the housing, as their bases can differ from that of a standard halogen bulb. Ensure any aftermarket LED kit you purchase is designed for your Altima's specific year and model.
• Beam Pattern: While LEDs are brighter, their light output can sometimes be scattered or have an improper beam pattern in housings designed for halogen bulbs. This can reduce effective illumination and potentially blind oncoming drivers. Look for LED bulbs that mimic the filament placement of their halogen counterparts to ensure a proper beam pattern.
• Color Temperature: LED bulbs typically come in a cooler white light (e.g., 6000K-6500K) compared to the warmer yellow light of halogens. While this is often desired, ensure the color temperature is legal in your region for exterior lighting.

How to Replace Each Bulb

• Headlights (Low/High/Fog): Access is usually from the rear of the headlight assembly. Twist the bulb counter-clockwise to remove, disconnect the electrical connector, and then reverse the process for the new bulb. For some models, fender liner removal or partial bumper removal might be necessary for easier access.
• DRL/Front Turn Signal: Often accessed by twisting the bulb socket out from the headlight assembly or behind the fender liner.
• Rear Turn Signal/Brake/Tail/Reverse: Typically involves removing the tail light assembly from the vehicle. This usually requires removing a few screws or nuts accessible from inside the trunk, and then carefully prying the assembly away from the body.
• License Plate Lights: Access is usually from behind the rear bumper or trunk lid trim. Twist the socket out to replace.
• Side Marker Lights: Often accessed by carefully prying the lens cover off or by reaching behind the housing from the wheel well.
• Dome/Map Lights: Carefully pry off the lens cover with a plastic trim tool or small flathead screwdriver. The bulbs are usually pushed or clipped into place.

Always consult your owner's manual for specific instructions and safety precautions before attempting any bulb replacement.

Common Lighting Issues for this Generation

• Premature Halogen Burnout: While not exclusive to the Altima, some owners report halogen bulbs (especially headlights) burning out sooner than expected. This can sometimes be due to voltage fluctuations or simply the lifespan of the bulb.
• DRL Malfunctions: On models with integrated LED DRLs, a failure can necessitate replacing the entire headlight assembly, which can be costly.
• Flickering After LED Upgrade: As mentioned, if not using CANBUS-compatible LEDs or load resistors, you may experience flickering or "bulb out" warnings for upgraded exterior lights.
• Moisture in Headlight/Tail Light Assembly: Over time, seals can degrade, leading to moisture inside the light housings. This can shorten bulb life and cause electrical issues.

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