The 1.6-litre unit had been fitted to modestly powered Sevens since 2006, when the previously popular Rover K-series engine disappeared with the demise of MG Rover.
The Ford unit revved less highly than the K but made a broad spread of power and over the past decade and a half has been offered in various outputs of between 120bhp and 150bhp. It is also the power source for Caterham's entry-level Academy race cars, which will retain the powerplant for 2022.
Most recently it received throttle bodies and over-sized air filters on the Super Seven 1600 model, which appeared as a benchmark wildcard in Autocar's Britain's Best Affordable Driver's Car contest.
For the immediate future, the range will be smaller. Caterham's new 660cc Suzuki-engined 170 model with 85bhp props up the bottom of the range, priced from £22,990.
Ford's 2.0-litre Duratec is the only other powerplant, offered in 180bhp, 210bhp or 310bhp forms for the 360, 420 and 620 models respectively, with prices from £31,490 to £50,390.
The gap between 170 and 360 models left by the Sigma engine's demise will be filled next year when new, sub-150bhp versions of the 2.0-litre Duratec engine are homologated.