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HID Xenon bulbs are high-intensity discharge headlights that produce bright, white light and are commonly used in many vehicles for improved nighttime visibility.
Among them, D1, D2, D3, and D4 are the most widely used types. However, their similar appearance often leads to confusion for drivers and DIY enthusiast when replacing or upgrading bulbs. Each type has specific voltage, connector, and ballast requirements.
In this guide, we’ll help you quickly and accurately identify your HID bulb type to avoid costly mistakes.
What Are HID Xenon Lamps?
HID systems, also called gas discharge bulbs, produce up to 200% more light on the road than standard halogen bulbs.
They work by creating an electric arc between two tungsten electrodes, which then ignites a mix of xenon gas and metallic salts to produce a very bright light.
HID headlights can produce between 2,800 and 3,500 lumens using 35 to 85 watts of power at 12.8 volts. In comparison, halogen bulbs typically produce 700 to 2,100 lumens using 40 to 72 watts.
On average, HID bulbs last around 2,000 hours, much longer than halogen bulbs, which only last 450 to 1,000 hours.
To ignite an HID bulb, a very high voltage is needed—up to 26,000 volts. That’s why HID systems require a ballast, which controls the power, and a starter, which helps ignite the bulb.
Want to know how HID stacks up against LED in real-world performance? Check out our detailed comparison: LED vs HID Headlight Bulbs: Who is The Winner?
HID Bulb Naming Explained
If your HID bulb is broken, don’t think you can just buy any HID bulb and be done with it! HID bulbs come in many different types like D1S, D2S, D2R, D4S, D3S… and those letters and numbers aren’t random — they follow a specific format that tells you how the bulb functions and where it should be used.
HID bulb models typically follow a three-character code, like ‘D4R’, ‘D1S’, ‘D3S’, etc.
Here’s what each part of the code means:
▪️ D = Discharge (HID) bulb
▪️ Odd numbers (1, 3) = With built-in igniter
▪️ Even numbers (2, 4) = No built-in igniter, require a separate external igniter
▪️ 1 & 2 = Contain mercury (older design)
▪️ 3 & 4 = Mercury-free (eco-friendly design)
▪️ S = For projector lens use
▪️ R = For reflector bowl use
For Example:
D1S = HID bulb with built-in igniter, mercury content, designed for projector lenses.
These HID’s of ‘D’ series always have a quartz envelope and arc positioned in the same place. They do not run on low-voltage DC current, but require ballasts with external or internal igniters that convert the power into AC and make a high voltage pulse to produce a spark.
D-Series HID Bulb Comparison
HID Type | Image | Igniter | Mercury | Application | Ballast | Base Type | Voltage |
|---|---|---|---|---|---|---|---|
D1S |  | Built-in | Yes | Projector | External | PK32D-2 | 85V |
D1R |  | Built-in | Yes | Reflector | External | PK32D-3 | 85V |
D2S |  | External | Yes | Projector | External | PK32D-2 | 85V |
D2R |  | External | Yes | Reflector | External | PK32D-3 | 85V |
D3S |  | Built-in | No | Projector | External | PK32D-5 | 42V |
D3R |  | Built-in | No | Reflector | External | PK32D-6 | 42V |
D4S |  | External | No | Projector | External | P32D-5 | 42V |
D4R |  | External | No | Reflector | External | P32D-6 | 42V |
To provide a clearer illustration, refer to the image below:
1. Ignitor Type: Integrated (D1, D3) vs. External (D2, D4)
- Built-in igniter: D1S, D1R, D3S, D3R
- No built-in igniter: D2S, D2R, D4S, D4R
2. Voltage Difference: 85V (D1, D2) vs. 42V (D3, D4)
- 85V 35W: D1S, D1R, D2S, D2R
- 42V 35W: D3S, D3R, D4S, D4R
3. Bulb Type Use: ‘S’ in Projector vs. ‘R’ in Reflectors
- For Projector Headlight: D1S, D3S, D2S, D4S
- For Reflector Headlight: D1R, D3R, D2R, D4R
HID Bulb Socket Identification
What if you’re handed a D1R and D3R or a D2S and D4S without any labeling? Since you can’t visually confirm the presence of mercury—and therefore the voltage—you can identify them by checking the notches on the bulb base.
You can tell the difference between D2 and D4 lights looking at the bulb base.
You can distinguish between D1 and D3 bulbs by examining the connector layout on the ignitors. While both types may appear similar at first glance, the key difference lies in the keying position: the D1 bulb features a notch on the top-left corner of the connector, whereas the D3 bulb has its notch positioned on the bottom-left corner. This subtle variation allows for accurate identification when labels are missing.
Aftermarket HID Bulbs: Type-C Bulb
Type C HID bulbs exist because aftermarket manufacturers are always looking to simplify production and cut costs. Instead of making separate D4S (for projectors) and D4R (for reflectors), they realized both use the same base and arc position—the main difference is just the shield and coating.
So, they created what’s often labeled a D*C, an unofficial “combo” bulb that fits both. You won’t see D*C HID bulb from Philips or Osram, but it’s super common in budget brands. It’s cheaper to produce, easier to stock, and convenient for users who aren’t sure which one they need.
Aftermarket manufacturers don’t want to make a ton of different models. So they simplify: D1C replaces both D1S, D1R; D2C replaces both D2S and D2R. D4C can fit D4S, D4R, and even D2C sockets in some cases.
How To Replace Your HID To LED Headlight Kits Easily?
If your car came with factory-installed HID headlights and you’re considering upgrading to LED, you’re not alone. Many drivers want to switch to LED for their faster startup time, improved energy efficiency, and brighter, more focused beam. But before diving into the installation, it’s common to have a few concerns—like “Will LED headlight bulbs be plug-and-play with my OEM HID setup?” or “Do I need to buy a separate ballast or canceler to make them work?”
Basically, there are two main types of LED headlights for replacing HID: one offers a plug-and-play installation, while the other requires manual modification or need a set of wiring harness.
To see how it works in real life, check out this successful HID-to-LED conversion case by NAOEVO. The best option for you depends on your original bulb type and your specific needs.
Type 1: Need Extension Wiring For Installation
First of all, let’s take a look at this diagram below so you will get a clear idea on how to hook up all the parts.
Here is the step by step installation guide:
Step 1 : Remove the dust cover from the headlight housing to find the HID Bulb inside. Press and open the clip and take out the original HID Xenon bulb.
Step 2: Take off the wires and igniter from the ballast.
Step 3: Take off the chuck from the LED bulb and lock it by the clip, then put the LED bulb into the chuck.
Step 4: Find “+” pole and “-” pole wire and connect them to the factory ballast power plug
Step 5: Put the ballast back to the original place before unloading all wires or igniter.
Type 2: Direct Plug-n-Play Installation
These LED headlight bulbs are designed with the same power plug as your original HID bulbs, so there’s no need for additional wiring.
Here is the step by step installation guide:
Step 1: Open the cover.
Step 2: Disconnect and take out the HID bulb.
Step 3: Connect the power plug to LED headlight bulb.
Step 4: Insert the LED bulb to the headlight housing.
Step 5: Put the cover back.
HID to LED Headlight Conversion: Which Type of LED Bulb Should I Choose?
When replacing HID headlights with LED, choosing the right type of LED bulb depends on your car model and wiring system. Here’s a simple breakdown to help you decide:
Type 1: LED Headlight Bulbs with Additional Wiring Harness
This type is ideal for older-model vehicles. Many older cars do not have built-in Canbus systems compatible with LED technology. Upgrading to LED in these vehicles can often trigger error codes, flickering, or even headlight failure.
By using an additional wiring harness or an external driver with built-in Canbus decoders, you can improve compatibility and ensure stable performance. This setup allows for a smoother conversion and minimizes electrical issues.
Type 2: Plug-and-Play LED Headlight Bulbs
For most modern vehicles—especially European brands like Audi, BMW, or Volkswagen—a plug-and-play LED bulb is often the best choice. These bulbs are designed to match the original HID socket and power configuration, offering a hassle-free installation without the need to cut or modify any wiring.
They’re built with integrated Canbus systems to prevent dashboard errors and ensure full functionality with your car’s electronics.
Best Plug-n-Play LED Bulb For HID Upgrade
| Replace For: D1S/D1R NAOEVO D1 Pro LED Headlight
|
 | Replace For: D3S/D3R NAOEVO D3 Pro LED Headlight
|
 | Replace For: D2/D4 NAOEVO HD2/4 LED Headlight
|
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