"S"
SBC - Single Bed Converter
SBEC - Single Board Engine Controller
SC - Supercharged
SEFI - Sequential Electronic Fuel Injection
SES - Service Engine Soon (light)
SFI - Sequential (Port) Fuel Injection
SIL - Shift Indicator Light
SIR - Supplemental Inflatable Restraint
SIPS - Side Impact Protection System
SOHC - Single Overhead Cam
SPFI - Sequential Port Fuel Injection
SPOUT - Spark Output
SPK - Spark Control
SOL or Sol. - Solenoid
SRI - Service Reminder Indicator
SRS - Secondary Restraint System
SRS - Supplemental Restraint System (air bag)
SRT - System Readiness Test
SS - Speed Sensor
SSI - Solid State Ignition
STAR - Self-Test Automatic Readout
STFT - Short Term Fuel Trim
STO - Self-Test Output
SUB-O2 - Sub Oxygen Sensor
Sw. - Switch
SWB - Short Wheel-Base
Sys. - System