Collection: T4.2 Bulbs

The T4.2 bulb: intermediate indicator lights

The T4.2 belongs to the family of very compact plastic base miniature wedge bulbs. With a diameter of 4.2 mm, it sits between the T3 (the smallest) and the T5 (the most common).

It is used for dashboard indicator lights and specific indicators on certain dashboards — particularly on vehicles with detailed instrumentation requiring multiple miniature indicator lights.

Which T should I choose for my dashboard?

Four main diameters in the T family for dashboards:

• T3 (3 mm) — the most discreet indicator lights, thin warning lights
• T4.2 (4.2 mm) — intermediate speedometer indicator lights (this page)
• T4.7 (4.7 mm) — slightly larger variant, speedometer indicator lights for certain vehicles
• T5 (5 mm) — the most universal, speedometer and instrument backlighting

To identify the correct size, remove the faulty bulb and measure the diameter of the glass with a caliper — or visually compare it with a known reference.

T4.2 LED: modernizing your indicator lights

Switching to T4.2 LED brings:

• Brighter light than the original halogen
• Almost unlimited lifespan — particularly useful for hard-to-reach indicator lights (requiring dashboard removal)
• Color choice to customize the dashboard ambiance (white, blue, amber, red)

For a homogeneous result, replace all dashboard bulbs at once — avoid mixing halogen/LED, which creates visually distracting color differences.