The9003 vs H4 bulbs are two very different models that serve different purposes. The 9003 is meant for use on the road, while the H4 is better suited for off-road vehicles. Additionally, the H4 has a different base than the 9003, so it cannot be placed into a 9003 socket. Brent Ordway is an ASE-certified car technician.

Thesebulbs are manufactured to a high standard, they are ECE certified and meet all relevant regulations. These bulbs produce an increased vision of 60% to give drivers better clarity, improving safety and increasing the time available to react. This is a set of two H4 bulbs so you can change both headlamps at the same time.

Alrighty this is a fun one! I went through this many years ago when I converted to e code H4 housings with Hella 110w bulbs. Even though the sealed beam and the H4 bulbs use the same connector they do not have the same wiring. You need to swap two of the wires: Verify with a multimeter but this should put you on the correct path.
Onthe left is an OEM H4 halogen bulb and on the right is a HogWorkz H4 LED Headlight Bulb upgrade. Photo by Joe Zito. Best motorcycle headlight upgrade options. They can produce about three times the amount of light as a halogen bulb using the same or less power. I personally recall going from halogen to HID headlamps for
TheLED H4 bulb and the 9003 bulb are often considered interchangeable because they share the same physical dimensions and electrical connections. The H4 and 9003 bulbs are dual filament bulbs commonly used in automotive and powersport headlights, serving both high and low beam functions. This interchangeability makes it
Postedother thread also. It's right. The 9003st is the Sylvania (american) version with the slight blue tinting. As LGL002 said it's the same bulb, ALL of Europe knows it as H4. The US has to be a little different. European lighting requirements / restrictions far surpass US DOT. Read ANY lighting forum and all you get is how poor CitroënC5 Aircross. From £22,370. Save up to £1,867 from RRP. View all deals. However, motorists aren’t great at making sure their own cars don’t dazzle oncoming drivers; up to 71% could JQn4GI.
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    • are all h4 bulbs the same