2025 Land Rover Discovery L462 Rear Left Side Tail Light MY42-13A421-AC Genuine

Part number MY42-13A421-AC. We take parts off vehicles every week, and this page is updated with a link straight to the part as soon as another one arrives.

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About part number MY42-13A421-AC

A tail light is an electrical illumination component that forms part of the vehicle's exterior lighting system. Mounted at the back of the vehicle, it connects to the main wiring harness and houses bulbs or light-emitting diodes that illuminate when the driver operates the light switch or applies the brakes. When functioning correctly, it helps the driver remain clearly visible to trailing traffic in darkness or poor weather.

To confirm that this component is the correct item for your vehicle, you must check that your original part displays the manufacturer part number MY42-13A421-AC. This number is typically stamped or printed onto the plastic rear housing or mounting casing on the back of the unit. Matching the exact part number is the only way to ensure correct fitment and function.

Tail lights are commonly replaced after sustaining physical damage, such as cracks or water ingress from a light impact, or due to internal electrical failures. When installing a replacement light, a technician or owner often requires fresh fixing clips, replacement bulbs, or a new foam sealing gasket to prevent water leaking into the bodywork.

About this kind of part: rear lamps

A rear lamp holds several separate functions in one housing: the tail light, the brake light, the indicator, the reversing light and the rear fog light. On most cars one lamp carries the reversing light and the other carries the rear fog light, so the two sides are not mirror images of each other in what they actually do. The light source is a bulb or a set of light-emitting diodes, and a diode lamp cannot be converted to bulbs.

Why people replace one

  • The lens has cracked, usually from a knock while reversing, and water has got into the housing.
  • The red lens has faded to pink where it has stood in the sun, which shows most on an older car.
  • A diode section has gone dark in patches, which cannot be repaired because the diodes are sealed into the unit.
  • The housing is sound but a mounting stud or lug has broken, so the lamp no longer pulls up tight against its seal and lets water past.
  • Condensation sits inside after rain, because a bulb holder seal or a breather has perished.

Fitting it

  • Most rear lamps are reached from inside the boot or the tailgate aperture, behind a trim panel or a removable cover.
  • The lamp is held by two or three nuts on studs and then pulls straight back out of its locating pegs.
  • The foam or rubber seal around the back of the lamp is what keeps water out of the boot. If it has hardened, water will find its way in whatever else is done.
  • On a car with diode lamps the car may watch the current drawn by each function, so a mismatched unit can log a fault.

Making sure it is the right one

  • Match the part number, not the side of the car. The reversing light and the rear fog light sit on opposite sides, and markets that drive on the left put them the other way round from markets that drive on the right, so a lamp can look like the wrong side and still be the correct part.
  • A bulb lamp and a diode lamp for the same model share the aperture and will bolt in, but the car will not operate them correctly and the connector differs.
  • Count the connector pins and compare the block shape with your own lamp.
  • Compare the pattern of the lens sections. A facelift often reshapes the internal pattern while keeping the outer shape, so the number is the only reliable test.

What to look for in the photographs

A Part number — On a printed label on the back of the housing, or moulded into the plastic near the connector.
B Connector block — The plug on the back. Count the pins and compare the shape, because a bulb unit and a diode unit differ here.
C Function layout — Which section is the reversing light and which is the rear fog light. These sit on opposite sides of the car, and the other way round in markets that drive on the other side of the road.
D Mounting studs and lugs — The threaded studs and locating pegs on the back. A broken one means the lamp cannot be pulled tight against its seal.
E Seal face — The foam or rubber seal around the back edge. This is what keeps water out of the boot.
F Lens surface — Look at the lens at an angle rather than straight on, which shows up fine crazing and any fading that a flat photograph hides.

This section describes rear lamps parts in general. The numbers and the photographs above are this part.

Free next-day delivery in the United Kingdom Sent with DPD on a tracked, next-day service. Most mainland addresses are next day; the Highlands and Islands, Northern Ireland, the Channel Islands and the Isle of Man can take a day longer.

Returns Thirty days to change your mind, and we pay the return postage in the United Kingdom and Germany.

Trade and VAT C.E.J Haime Group Limited is VAT registered in England and Wales, and every order comes with a full VAT invoice.

Not sure it is the right part? Send us your registration or VIN and we will check this part number against your own vehicle before you buy.

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