H4 LED Headlight Bulbs: How One Bulb Makes High and Low Beam

Short answer: An H4 LED headlight bulb is a dual-beam LED replacement for the halogen H4, one bulb that has to make both the low beam and the high beam. PIAA lists the halogen H4 with 2 filaments at 60/55 W, and Osram lists 1650/1000 lm on a P43t base. TUHO lists 14 H4 LED models, from 2,850 LM to 25,000 LM per set, so the buyer’s questions are how the beam switches, how much heat the bulb makes and whether it fits behind the lamp.

Key takeaways

• The halogen H4 has two filaments in one bulb. PIAA lists 60/55 W, and Osram lists 60/55 W, 1650/1000 lm and a P43t base.
• All 14 models in TUHO’s H4 category list H4 as a dual-beam socket; they differ in lumens, power, voltage range and cooling.
• The product pages do not describe how each bulb switches beams, so ask the supplier and test the beam pattern on a wall.
• Three models (X02, X01-S and X01-L) list more than 146W per set, so each bulb can draw more than the halogen’s maximum input.
• H4 is a different bulb from H1, H7 and 9005; those are single-beam sockets.

What is an H4 bulb, and how does a halogen H4 make high and low beam?

An H4 bulb is a halogen headlight bulb with two filaments in one glass capsule, so one bulb provides both the low beam and the high beam. PIAA’s cross-reference lists the H4 with 2 filaments and “6 V & 12 V: 60 / 55 W”, against 1 filament for the H1 (PIAA cross-reference).

Osram’s catalog gives the baseline an LED replacement is compared against. Its ORIGINAL LINE H4 (order reference 64193) is a 12 V lamp with these listed values (Osram ORIGINAL LINE H4):

• Power: 60/55 W nominal, 75/68 W maximum input.
• Light output: 1650/1000 lm nominal at a 13.2 V test voltage.
• Base: P43t, ECE category H4.
• Life: B3 250/400 hr and Tc 500/900 hr, listed separately for the two filaments.

Osram’s page does not say which filament is the high beam, so check the vehicle manual rather than guessing.

How does an H4 LED bulb make high and low beam from one bulb?

An H4 LED bulb has to reproduce both filament positions with LED chips, and the design decides how good the beam is. A reflector or projector lamp is built around the place where the filament sits, so chips in the wrong place scatter light.

• One light source, two beams: The bulb must give a low beam with a clean cut-off and a high beam from the same socket, without extra wiring in the lamp.
• Chip position: The chips should sit where the filaments sat, and the bulb should lock in the correct orientation.
• Beam check: After fitting, check both beams against a wall and re-aim the lamps if needed.
• What TUHO lists: The product pages list H4 as a dual-beam socket for each model but do not describe the switching design or give beam-pattern data, so ask for photos and a sample.

For aim and beam checks, see our guide on how to aim your headlights, and for the lamp types, our comparison of projector vs reflector headlights.

How do TUHO’s H4 LED headlight bulbs compare?

TUHO’s H4 category lists 14 models, from 2,850 LM (V20 Tri-Color) to 25,000 LM (X01-L) per set. The table shows the figures as the product pages give them, and every figure is for one set, meaning a pair of bulbs.

Model	Listed lumens per set	Listed power per set	Voltage	Notes from the product page
V20 Tri-Color	2850 LM	35W-30W	9-32V	Tri-color / dual-color
V23	3000 LM	35W-30W	9-36V	Truck specific; 0.135 kg per H4 set
Z2	3200 LM	35W-20W / 22W	9-32V	Direct insertion, linear drive; 0.104 kg per H4 set
Z2S	3300 LM	33W-20W	6-32V	Direct insertion, Canbus-ready, no polarity
V20	5200 LM	60W-45W	9-32V or 9-60V	6000K, 4300K and 3000K; 12V and 24V versions
V18	5900 LM	65W-52W	12V-24V	6000K; 0.243 kg per H4 set
V28	6000 LM	65W-52W	9-60V	Trucks and cars
S01-H4	6000 LM	64W	9-32V	Copper base plate, silver aluminum, 46.8 g
V25	8000 LM	55W-50W for H4	9-32V	Canbus-ready
V27B	8000 LM	120W-70W	9-32V	15 chips of 4575 beads; digital display version also listed
12V 12000LM model	12000 LM	126W	12V	6 chips of 3570 beads
X02	20000 LM	200W	9-60V	2 copper pipes
X01-S	24000 LM	245W	9-60V	3 copper pipes, small fan
X01-L	25000 LM	250W	9-60V	3 copper pipes, big fan

Read these numbers as listed values, not measured results. The product pages give no test method, so ask how the lumens were measured before you compare models or brands.

• Per set, not per bulb: Halve a set figure to get one bulb. A 3,200 LM Z2 set works out to 1,600 LM listed per bulb.
• Not comparable to halogen lumens: Osram’s 1650/1000 lm is per bulb for a halogen filament; LED set figures are a different measure, so do not compare them directly.
• Color temperature: Most models list 6000K, and S01, the X-series and the 12000LM model list 6000-6500K. V20 adds 4300K and 3000K.
• Rated life: The product pages rate Z2, Z2S, V20 Tri-Color and V23 at 30,000 hours or more, and the others at 50,000 hours or more. These are listed ratings, not field data.

How much heat does an H4 LED bulb make, and will it fit?

Heat rises with listed power, so a high-power H4 LED bulb needs more cooling hardware and more room behind the lamp. Fitment is the top cause of H4 returns, because many H4 lamps have a dust cover and little space.

• Power per bulb: Split the set figure by two. The 12V 12000LM model lists 126W per set, about 63W per bulb, and X02 lists 200W, about 100W per bulb.
• Against the halogen: Osram’s maximum input for the halogen H4 is 75/68 W. X02, X01-S (245W) and X01-L (250W) list more than twice that per set, so each bulb can exceed it.
• Cooling hardware: X02 lists 2 copper pipes, and X01-S and X01-L list 3 copper pipes with a fan. Z2 is a compact direct-insertion design.
• Weight as a clue: Z2 lists 0.104 kg per H4 set and V18 lists 0.243 kg. The heavier bulb carries more cooling hardware.
• Start versus stable power: Many models list two figures, such as 65W-52W for V18. The first is the start power and the second is the stable power.

What wiring and Canbus problems should you expect with an H4 LED bulb?

Most wiring problems come from three things: the voltage range, polarity and Canbus behavior. Check all three against the vehicle before you stock a model.

• Voltage range: V28, X02, X01-S and X01-L list 9-60V, so one model covers 12V cars and 24V trucks. V18 lists 12V-24V, V23 lists 9-36V and the 12000LM model lists 12V only.
• Polarity: Z2S lists no polarity, so it works whichever way it is plugged in. If another model does not light, try turning the plug over before you blame the bulb.
• Canbus: Z2S and V25 are listed as Canbus-ready, which is meant for cars that show a bulb-out warning with ordinary LED bulbs. Our Canbus vs non-Canbus guide explains why.
• Flicker or no light: Check that the connector is fully seated and locked before you suspect the bulb. Do not cut or splice the vehicle harness.

A typical installation follows these steps. Always use the instruction sheet for the exact model.

1. Confirm the number: Read H4 on the old bulb or in the owner’s manual.
2. Remove the old bulb: Switch the lamp off, let it cool, remove the dust cover, disconnect the connector and take the halogen out.
3. Fit the LED bulb: Seat the base without force, in the orientation the instructions show, then connect the plug.
4. Check the clearance: Make sure the heatsink, fan or driver does not touch the housing or block the dust cover.
5. Test both beams: Switch to low and high beam, watch the dashboard for warnings, then check the aim against a wall.

How is H4 different from H1, H7 and 9005?

H4 is a dual-beam bulb, while H1, H7 and 9005 are single-beam bulbs, so they are not interchangeable. PIAA lists H4 with 2 filaments and H1 with 1 filament.

Halogen type	Filaments (PIAA)	Stock power draw (PIAA)	Role
H4	2	6 V & 12 V: 60 / 55 W	Low and high beam from one bulb
H1	1	6 V & 12 V: 55 W	Single beam
HB3 (9005)	1	12 V: 60 W	Single beam
HB4 (9006)	1	12 V: 51 W	Single beam

• H4 vs 9003: They are two names for closely related bulbs; see our guide on whether H4 is the same as 9003.
• H4 vs 9005: The 9005 is a single-beam bulb on a different base; see our 9005 LED headlight bulb guide.
• One bulb, one beam: A lamp that uses two single-beam bulbs needs a different bulb type from an H4 lamp. Do not assume the sockets match.

Are H4 LED headlight bulbs legal, and what should importers check?

Legality depends on the destination market, so importers should confirm the rules and the supplier’s documents for each market and each model.

• US definition: FMVSS No. 108 defines a replaceable bulb headlamp as a headlamp with a bonded lens and reflector assembly and one or two replaceable light sources (49 CFR 571.108).
• NHTSA position on LED headlamps: In December 2022 NHTSA said that using LED technology in an integral beam headlamp does not make the headlamp noncompliant. It also said that decision does not address other headlamp types such as replaceable bulb headlamps (Federal Register, 2022-26658).

This article does not say that any H4 LED bulb meets DOT, ECE or any other approval. TUHO matches products to the destination market’s rules, and the required documents are confirmed per model and per order.

What should distributors stock in H4 LED bulbs?

Stock one compact model, one Canbus-ready model and one wide-voltage model, then add high-output SKUs only where customers ask for them.

• Compact fit: Z2 and Z2S suit lamps with little room. Z2S adds Canbus-ready operation and no polarity.
• Mainstream cars: V25 lists 8000LM, Canbus-ready operation and a 9-32V range, with 55W-50W for H4, and it also covers H1, H7, H11, 9005, 9006 and 9012.
• Trucks and mixed fleets: V28 lists 9-60V, so the same SKU serves 12V and 24V vehicles. V23 (9-36V) and V18 (12V-24V) are the other options.
• High-output: V27B and the X-series list the highest outputs. They need space and cooling, so expect more fitment questions and returns in tight H4 lamps.

For an OEM or private-label order, confirm these parameters in writing:

• Electrical: Voltage range, power at start and when stable, and Canbus behavior.
• Mechanical: Bulb dimensions, weight and base orientation for the H4 version.
• Light: Color temperature, how the lumens were measured, and how the bulb makes both beams.
• Packing: Color box, outer carton, logo and sets per carton.

How TUHO supplies this category

TUHO Lighting is an automotive LED lamp manufacturer in Dongguan, Guangdong, and it lists 14 H4 LED headlight bulb models in its H4 LED headlight bulbs category.

• OEM and ODM: TUHO supports OEM and ODM projects; see the OEM/ODM page for the order process.
• Custom branding: Custom logo, color box and outer carton are supported.
• Mixed orders: Small batches and mixed-SKU orders are supported, which suits e-commerce sellers and shops testing a range.
• Lead time: Delivery is usually arranged within 1-10 working days, depending on quantity. Minimum quantities and prices are confirmed per order.
• Warranty: The product pages for V25, V28, V27B, S01, X02, X01 and the 12000LM model list a 2-year warranty. Check the page of the model you want.
• Quality steps: TUHO’s quality-control process includes burn-in testing, lumen testing and waterproof testing, among 12 steps.

Sourcing H4 LED headlight bulbs for your range? Send us your sockets, vehicle markets and target quantity. TUHO can quote OEM/ODM orders with custom logo and packaging, mixed SKUs, and samples for testing. Request a quote

FAQ

How does an H4 LED bulb work as both high and low beam?

An H4 LED bulb works as both high and low beam by using LED chips placed to reproduce the two halogen filaments. Designs differ, and TUHO’s pages do not describe the switching method, so ask the supplier and check the beam pattern on a wall.

Is H4 the same as HB2 and 9003?

H4 is closely related to HB2 and 9003, which are US names for a dual-beam bulb. PIAA lists the H4 as similar to the US HB2 (9003), so confirm the marking for your market.

Can I use an H7 LED bulb in an H4 headlight?

No, an H7 LED bulb does not fit an H4 headlight. H4 is a dual-beam bulb with a different base, and H7 is a single-beam bulb, so buy the type the lamp is made for.

Do H4 LED bulbs need a Canbus decoder?

Only some H4 LED bulbs need a decoder, and it depends on the car. V25 and Z2S are listed as Canbus-ready, which is meant for cars that show a bulb-out warning with ordinary LED bulbs.

Can an H4 LED bulb run on a 24V truck?

Yes, some H4 LED bulbs run on 24V. V28, X02, X01-S and X01-L list 9-60V, V23 lists 9-36V and V18 lists 12V-24V.

Bottom line: Pick an H4 LED headlight bulb by how it makes both beams, its voltage range and the space behind the lamp first, and by listed lumens second. Ask for beam-pattern photos and a sample, because the product pages do not show how each bulb switches beams.

Editorial note: Product figures were read from the live TUHO product pages on 26 October 2026 and are catalog values, not independent test results. Per-bulb power is the listed per-set power divided by two. Halogen H4 figures come from Osram’s ORIGINAL LINE H4 catalog page (read 26 October 2026) and filament counts from PIAA’s cross-reference page. US rules come from the eCFR text of 49 CFR 571.108 and from NHTSA’s December 2022 Federal Register notice. UNECE Regulation No. 37 could not be opened, so this article does not rely on it.