What is an H15 bulb? Main beam and DRL in one
An H15 bulb is a twin-filament halogen headlamp bulb rated 55/15 W. The 55 W filament provides main beam and the 15 W filament provides the daytime running light (DRL), so one bulb does both jobs on each side. It uses its own PGJ23t-1 base, so no other bulb will fit in its place.
Of the 360 UK car generations we've verified, 21 use an H15 for main beam. Two well-known examples are the VW Golf Mk7 and Skoda Octavia Mk3, both of which pair an H7 dipped beam with an H15 main beam.
What is an H15 bulb used for?
The H15 exists to save space and parts. Instead of a separate bulb or LED strip for the daytime running light, the car uses a second, lower-power filament inside the main beam bulb.
H15 | |
|---|---|
| Filaments | Two |
| Wattage | 55 W main beam / 15 W daytime running light |
| Base | PGJ23t-1 |
| Usual partner bulb | H7 dipped beam |
| Main beam in our data | 21 generations |
Read the code the usual way: the slash in 55/15 W means two filaments, and each number is one filament's wattage. Our guide to reading car bulb codes covers the system in full.
Why did my daytime running light go out with my main beam?
Because they're the same bulb. If either filament in an H15 fails, the whole bulb needs replacing, and you'll often notice it first as a daytime light missing on one side.
The DRL filament is the one that works hardest. It's lit whenever the car is being driven in daylight, so it builds up far more hours than the main beam filament. When one DRL goes dark, check main beam on the same side as well; it's the same part.
Depending on the car, the DRL may dim or switch off when you turn the headlights on. That's how the system is designed, not a fault, and it varies between makes and models. Your handbook explains how your car's lights behave.
Can I use an H7 instead of an H15?
No. The H7 has one filament and a PX26d base; the H15 has two filaments and a PGJ23t-1 base. An H7 won't lock into an H15 holder, and it couldn't provide the daytime light even if it did.
The same applies the other way round. The H7 in the dipped beam position of a Golf Mk7 or Octavia Mk3 is a separate bulb, and you'll need both codes if you're stocking spares. Our H7 vs H4 vs H1 guide explains the single-filament bulbs.
Which cars use an H15 bulb?
In our verified data, these generations use an H15 for main beam:
| Car | Dipped beam | Main beam |
|---|---|---|
| VW Golf Mk7 2012–2020 | H7 | H15 (also runs the DRL) |
| Skoda Octavia Mk3 2013–2020 | H7 | H15 |
These values are for halogen headlamps. Where a generation was also offered with xenon or LED headlamps on some trims or after a facelift, those versions use different parts, so the bulb list can split within one generation. The car page shows any split. If you're not sure which headlamps you have, see halogen, xenon or LED: how to tell.
Should I replace H15 bulbs in pairs?
Yes, for the same reasons as any headlamp bulb. The bulb on the other side has done the same hours and may not be far behind, and a matched pair gives the same colour and output on both sides. With an H15 that matters twice over, because the daytime running lights are the lights other road users see most.
Our guide to replacing headlight bulbs in pairs covers this in more depth, including why you shouldn't touch the glass.
How do I change an H15 bulb?
On most cars the H15 is changed from behind the headlamp, under the bonnet. The general method is:
- Switch off the lights and ignition, and let the bulb cool.
- Find the main beam cover on the back of the headlamp and remove it.
- Unplug the connector, then twist or unclip the bulb.
- Fit the new bulb without touching the glass, holding it by the base.
- Refit the connector and cover, then test main beam and the daytime running light.
Access varies. On some cars there's room for a hand behind the headlamp; on others you need to remove trim panels or more. The step-by-step guide to changing a headlight bulb goes through the common variations.
Can I fit an LED H15?
Not into a halogen headlamp. The MOT inspection manual treats a halogen headlamp unit converted to LED or HID bulbs as a fail on vehicles first used on or after 1 April 1986. Factory-fitted LED headlamps are fine, but they're a different unit altogether. See are LED headlight bulbs legal in the UK.
Check your car
Confirm your main beam and DRL bulb by generation:
- VW Golf Mk7 bulbs
- Skoda Octavia Mk3 bulbs
- Audi A3 8V bulbs and SEAT Leon 5F bulbs, which share a lot with the Golf but use
H7for both beams
Or browse every car we cover on the bulbs page.
Common questions
What does H15 mean on a bulb?
H15 is the standard type number for a 55/15 W twin-filament halogen bulb on a PGJ23t-1 base. Like other headlamp codes, the number identifies the type rather than the wattage.
Is the H15 bulb the DRL bulb on a Golf Mk7?
On halogen-headlamp versions, yes. The H15 provides main beam and the daytime running light, so a dead DRL usually means the H15 on that side needs replacing.
Will my MOT fail if a DRL is out?
The MOT checks headlamp operation and aim, so a failed H15 that stops main beam working will be a problem. Daytime running light rules are more detailed; the MOT inspection manual sets out exactly what's tested.
Is an H15 the same as an H7?
No. They have different bases, different numbers of filaments and different jobs. On a Golf Mk7 or Octavia Mk3 you'll find both: H7 for dipped beam and H15 for main beam.
Checked against our verification rules. Spotted something wrong? Tell us.