Seat Leon Headlights: Specs, Fitment & Common Faults

Bulb type, unit part numbers, and the faults that actually cause that flickering or dim light you've noticed.

Illustration for editorial purposes

Opens live listings in a new tab.

OEM Part Number: confirm via VIN — aftermarket LH Valeo 045100 / RH Valeo 045101

Accuracy note: Covers the Seat Leon (Mk3 2012-2020) as listed in the UK aftermarket catalogues. Headlights are sold by side (passenger / nearside = LH, driver's / offside = RH on a UK car) and by lamp type — halogen, xenon (D1S / D3S) and LED or full-LED units are not interchangeable, and DRL, cornering and levelling options change the part number again. The references below are UK aftermarket catalogue listings for this generation, labelled by brand; genuine numbers are shown only where a listing quotes one. Check the lamp type and traffic side (UK right-hand-traffic units, not LHD) against your VIN, and expect xenon / LED and adaptive units to need levelling adjustment or coding after fitting.

Passenger side (LH / nearside) headlight — aftermarket	Valeo 045100 (halogen H7, PY21W, with DRL, original part); Diederichs 7433381 (halogen H7, PY21W, with DRL, levelling motor, bulb included, Valeo quality); Van Wezel 4946961 (halogen H7/H7, with DRL, levelling motor); Abakus 445-1134LMLDEM2 (halogen H7, PY21W, P21W, levelling motor); TYC/Abakus LED unit Abakus 445-1134LMLEMN2 (H7/H7 with LED DRL, electric levelling); Valeo 045104 (LED headlight, with DRL, original part)
Driver's side (RH / offside) headlight — aftermarket	Valeo 045101 (halogen H7, PY21W, with DRL, original part); Diederichs 7433380 (halogen H7, PY21W, with DRL, levelling motor, bulb included, Depo/TYC quality); Van Wezel 4946962 (halogen H7/H7, with DRL, levelling motor); Abakus 445-1134RMLDEM2 (halogen H7, PY21W, P21W, levelling motor); TYC 20-17465-06-2 (H7/H7 with LED DRL, electric levelling); Diederichs 7433486 (LED, with LED DRL, facelift 2017 on, without control unit)
Bulb types	dipped/main H7, indicator PY21W, sidelight P21W; LED on full-LED trims
Genuine (OE) numbers quoted	None quoted in catalogue listings — order genuine units against your VIN
Fitment notes	Halogen H7 with LED DRL covers most trims and full-LED units (Valeo 045104/045105, Diederichs 7433486/7433487, Van Wezel 4949963/4949964) fit the LED trims and facelift cars; LED units are mostly supplied without control unit.

A Genuinely Important UK Rule Worth Knowing Before You Buy — Seat Leon Headlights

If your Leon has factory-fitted halogen headlamp housings, converting them to fit LED bulbs is treated as a definite MOT failure under the current inspection manual — this isn't a grey area or a minor advisory, since a housing designed for halogen doesn't distribute an LED bulb's light output correctly, which can genuinely dazzle oncoming drivers. If you want a genuine LED upgrade, the correct route is a complete headlight unit designed for LED from the factory, not a bulb swap into an existing halogen housing.

Seat Leon Headlights: Watch: Replacing It

🎬 Watch: DIY How to replace all headlight bulbs Seat Leon 5F MK3

Watch on YouTube ↗

All headlight bulbs, 5F

Before you buy: matrix LED, adaptive, and cornering headlight systems often require electronic coding to the car after a unit swap, even for a genuine like-for-like replacement — a headlight that isn't recognised by the car's electronics can trigger warning lights or fail to auto-level correctly. Check whether your specific trim has one of these systems before assuming a straightforward bulb-in, bulb-out job.

Seat Leon Headlights: What It Does

The Seat Leon's headlight unit job is positioning the main and dipped beam bulbs (or LED/matrix modules on higher trims) to light the road without dazzling oncoming drivers. That housing frequently also contains the daytime running light and front indicator, which is exactly why part numbers and repairs here can get complicated.

Seat Leon Headlights: Generations, Derivatives & Headlight Type

Standard trims	Halogen headlights on earlier generations/base trims
FR/Xcellence	Full LED dynamic headlights come as standard on these specific trims — genuine spec confirmed as 11 individually controlled LEDs per module producing up to 900 lumens, not just a bulb swap into the same housing
Fitment note	Halogen and full LED headlight assemblies use different electrical connectors (a 10-pin vs 14-pin plug is commonly cited) — retrofitting one type to a car built with the other genuinely requires coding, an adapter harness, and sometimes an upgraded body control module, not a simple swap

Find Seat Leon Headlights Here!

Opens live listings in a new tab.

Seat Leon Headlights: Common Faults, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Headlights Guide for the four bulb technologies and how they differ, UK law on aim and modifications, common faults to check for, how difficult this job is to DIY, and confirming fitment against your VIN.

More Seat Headlights

The same part, covered across other Seat models.