The Fiat 131 front and rear side marker bulbs both utilize a 194 bulb size for this model. The replacement chart covers 1975 through 1978 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 194 bulb is the sole bulb type specified for the Fiat 131's side marker lighting across all listed model years and positions.
The 194 is an ANSI-standardized bulb recognized in both the United States and Canada, which places it within a regulated performance and dimensional classification system.
It belongs to the T10 miniature wedge form factor, a base type that relies on two angled plastic legs rather than a metal screw or bayonet fitting to secure the bulb in its socket.
The 194 operates at 12 volts with a power draw of 3.78 watts, consistent with low-current auxiliary lighting applications such as side markers.
The Fiat 131 uses the 194 bulb for both the front and rear side marker positions across the 1975-1978 model years, meaning both positions share the same bulb specification without variation.
Because the T10 wedge base is a widely standardized form factor, the 194 is physically interchangeable with other T10-based bulbs, though electrical compatibility depends on matching voltage and wattage ratings.