What’s the difference between OEM xenon HID bulbs

Table of Contents

It is not new to auto headlamp for HID xenon burners that have been used over 25 years. Until now, there are only 10 models of factory installed HID bulbs: D1R, D1S, D2R, D2S, D3R, D3S, D4R, D4S, D5S, and D8S, comparing with so many types of aftermarket replacement xenon bulbs like H1, H4, H7, H11, 9005, 9006, D2H, D1C, D2C, D3C, D4C, etc.

So for those D series OEM bulbs, how to identify them and what are their differences?

D1S D1R D2S D2R D3S D3R D4S D4R D5S D8S HID xenon bulbs

Some knowledges of OEM HID bulbs

D is from “Discharge”, the same as the “D” in HID (high-intensity discharge).

The number 1, 2, 3, 4, 5, and 8 is the type, which also reveals the order of bulbs’ birth time. D1 is the first to use, then come out the others.

R and S decide on the bulb’s application.

D1R D2R D3R D4R is designed for reflector headlamps, which have a small non-transparent shield on the glass tube, helping avoid too much glare to the oncoming drivers.

D1S D2S D3S D4S D5S D8S are used in projector optics, and there is no such coat as R-type bulbs, thus making S bulbs have 300-400 more lumens. The headlights projector lens will adjust the lights into the proper direction.

reflector headlamp vs. projector optics headlamp

All of those HID lamps run on AC current because they need very high voltage to start and put out their light except D5S that on 12V DC.

As the first-used bulbs, D1R and D1S have igniters built into their base. Then D2 xenon bulbs do not have such ignitor inside, so they are smaller than D1 bulbs.

Both D1 and D2 lights contain heavy mercury and their power is 35W on 85V AC current.

Considering environmental protection, new D3 and D4 bulbs are produced without Hg (mercury) and they are not as bright as D1 and D2 HID bulbs.

Similar with D1 and D2, D3 types bulbs come with ignitor inside the base while D4 do not. So in summary, odd number 1 and 3 appear with built-in ignitor, even number 2 and 4 carry no ignitor.

Unlike D1 and D2, D3 and D4 operate on 42V but still 35W AC current. So all those bulbs cannot be exchanged with each other, no matter for reflector or projection type.

How to tell apart similar OEM xenon bulbs

It will be easy to differentiate S and R lights or with ignitor or not if with the knowledges above. But how to distinguish bulbs that almost have the same face? for example, D1R & D3R, D1S & D3S, D2S & D4S….

Sure it is easy to know bulbs type according to the marking label on them as Phillip or Osram does. But what if without such label?

First, for D1 and D2 bulbs, there is some hint on their ignitor connector. A small lump is on the top left corner of D1 lamps while for D2, it is on the opposite side, bottom left corner.

D1 D3 D8S HID lamps ignitor connector comparison

Then you can judge them by the notches position in the base of the factory bulbs. D1 and D2 follow the same rule, so do D3 and D4. You will see the point from the picture below.

D1S/D2S notches vs. D1R/D2R notches on their base
D3R/D4R notches vs. D3S/D4S notches on their base

D5S and D8S

Finally, we come to D5S and D8S HID bulbs. They are the newest so far. D5S is produced by Phillip but D8S by Osram after 2010. They are both 25W and mercury-free, which means lower lumens and less brightness than other OEM D lamps but more energy save. They are also environmental friendly.

D5S is the easiest one to be identified because of integrated ignitor and ballast, making their base the biggest among all.

D8S has built-in ignitor in its base as D1 and D3 bulbs and needs an extra ballast to start with stable voltage 42V. Also D8S is only for projector lens usage with letter “S”. We can recognise D8S by their base connector where the lump is on the bottom but center right (see the above photo).

So let’s summarize in a table:

Stable voltage85V85V85V85V42V42V42V42V12V42V
Nominal power35W35W35W35W35W35W35W35W25W25W
Mercury (Hg)YesYesYesYesNoNoNoNoNoNo
Built-in ignitorYesYesNoNoYesYesNoNoYesYes
Built-in ballastNoNoNoNoNoNoNoNoYesNo
Reflector or projectorR* (reflector)P* (projector)R*P*R*P*R*P*P*P*
Shield YesNoYesNoYesNoYesNoNoNo
Conclusin for OEM HID xenon bulbs

Some relative aftermarket HID bulbs

It is necessary to note here that you may get confused when see some bulbs that combine notches together with D1 D2 D3 D4. In fact, they are C type aftermarket bulbs as we metioned at first: D1C D2C D3C D4C. Though their bases may fit with each other, voltage differences cannot be neglected, D3 & D4 are made with different stable voltage comparing with D1 & D2. Appropriate ignitors and ballasts are must used.

Speak of similar aftermarket lamps, D2H xenon bulbs have to be metioned. D2H is also universal with 5 notches like C bulbs but with AMP connectors and usually applied for bi-xenon headlights lens. Like D1 and D2 bulbs, D2H is 85V with mercury.

D2H xenon bulbs C type bulbs base

D1S D2S D2H D3S D4S HID bulbs are often used for aftermarket bi xenon projector lens, such as ROYALIN hella 3R, Koito Q5, Bosch AL…. But different projectors with different sockets fit for different bulbs. What’s more, varying lighting output from different bulbs will be displayed even if a bi xenon projector is compatible with many lamps. For more details, please check the product introduction in ROYALIN website.

ROYALIN EVOX-R 2.0 bixenon lens, fit for D1S D2S D3S D4S D2H HID bulbs

Obviously you are a true fan and eager to know more of auto lights as you read far here. There are lots of useful  knowledge in our ROYALIN website with continuous renewal, enjoy yourself here! Please also feel free to contact us if any questions, we will spare no effort to help you.

Thank you very much for your valuable time here.


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Levi Chou

Levi Chou

Hi, I’m Levi Zhou, the founder of royalincarparts.com, I’ve been engaged in auto parts aftermarket for decades, and the purpose of this article is to share with you the knowledge relating to car lighting retrofit from a Chinese supplier’s perspective.

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