BMW 4 Series Tail Lights: Specs, Fitment & Common Faults
On the 4 Series, an official BMW bulletin genuinely explains taillights use waterproof membrane technology allowing natural condensation to escape — with example images distinguishing normal condensation from excessive water entry.
Illustration for editorial purposes
OEM Part Numbers
More Wiring Behind There Than Most People Assume
A tail light unit typically bundles several functions into one housing — brake light, indicator, reversing light and rear fog light — which means a single electrical fault can affect more than one function at once, and a "faulty tail light" can mean several genuinely different things.
What It Does
Beyond basic rear visibility, tail light units on the 4 Series typically integrate brake lights, indicators, reversing lights and rear fog lights into a single housing. Higher trims may use LED units with a distinct light signature, which are not interchangeable with standard halogen units even if the physical mounting looks similar.
Fitment & Compatibility
Tail light design changed between generations of the 4 Series, and facelifted versions within the same generation often use a revised light signature that isn't interchangeable with pre-facelift units. Always confirm the exact part for your specific model year before ordering. Whether you're sourcing a replacement tail lights for your BMW 4 Series from a dealer, specialist, or online marketplace, always check compatibility against your registration or VIN before buying, and confirm you're ordering the correct side — driver's side (RH in the UK) or passenger side (LH in the UK) — since these are not interchangeable.
Common Faults
What to Look For
- One function out but others working — often a single blown bulb rather than a wiring fault, since multiple bulbs typically share one housing.
- Condensation inside the lens — points to a failed seal, which can damage electrics if left untreated.
- Flickering brake light — can indicate a failing bulb holder or a wiring connection issue.
- Cracked lens from impact — usually straightforward to replace like-for-like, though LED units cost considerably more than halogen equivalents.
DIY Replacement Difficulty
Bulb replacement is usually an easy DIY job, typically accessed from inside the boot without needing tools. Full unit replacement is slightly more involved but still manageable at home on most versions, generally requiring removal of a few boot trim fasteners. Expect 10–20 minutes for a bulb swap, or up to 45 minutes for a full unit.
Confirmed: A Genuine Official Bulletin Worth Knowing About
If condensation has appeared inside a tail light, this is genuinely worth knowing directly from an official BMW service bulletin covering this generation specifically: these tail lights use waterproof membrane technology, which deliberately allows naturally occurring condensation and air to escape without letting excess water or dirt enter. The official bulletin includes example images distinguishing normal condensation, appearing along the edges of the lens and requiring no correction, from excessive water entry, which appears across the entire lens rather than just at the edges.
It's also genuinely worth knowing that a confirmed UK recall covering related BMW models from an earlier era addressed a wiring fault where corrosion on a power distributor plug could cause the car to completely lose power, shutting down all lighting including hazard lights, brake lights, and headlights.
OEM vs. Aftermarket
For basic halogen units, reputable aftermarket tail lights are a reliable, cheaper alternative to OEM. For LED units with a distinctive light signature, OEM or high-quality aftermarket replicas are worth the extra cost to avoid a mismatched look between the two rear light clusters.
More BMW Tail Lights Guides
The same part, covered across other BMW models.