Thermostat Housing
Engine Valve Cove
Intake Manifold
Expansion Tanks
Variable Valve Timing (VVT)

EGR Valve
Secondary Air Pump
Oil Cooler
Blower Resistor
Heater Valve
Throttle Body
Ignition Coil
Nitrogen Oxygen Sensor
Headlight Leveling Sensor
Oxygen Sensor
Temperature Sensor
Brake Light Switch
Fuel Pressure Regulator
Mass Air Flow Sensor
Oil Pressure Switch
ABS Sensor
Auxlliary Water Pump

Secondary Air Pump (Smog Pump, Air pump, Auxiliary air pump, Air injection pump))

The smog pump blows clean air into the exhaust until the engine reaches operating temperature. Once the exhaust gets hot enough, the extra air isn't required to lower tailpipe emissions and a valve opens to divert the air away from the exhaust. It's only purpose is to reduce exhaust emissions of a cold engine.