2007 Secondary Air Injection System; Secondary Air Pump - Subaru 2007 B-9 Tribeca Technicians Reference Booklet

2007 New Model Update
(916)

2007 SECONDARY AIR INJECTION SYSTEM

Turbo engines except the STi are equipped with a secondary air injection system.
The Secondary Air Injection System reduces harmful exhaust emissions by introducing a supply of
fresh air into the exhaust before it reaches the catalytic converter. The fresh air mixing with the hot
exhaust causes the unburned emissions to burn and brings the catalytic converter to operating
temperature must faster.
The fresh air enters the exhaust from behind a fresh air port located behind each exhaust valve. An
electric Secondary Air Pump provides the force necessary to supply the quantity of air needed for
mixing with the exhaust. The air from the secondary air pump is divided between the left and right
side of the engine. The fresh air is admitted into the exhaust by the action of a reed valve contained
in the left and right side combination valves. A metal pipe carries the fresh air to each cylinder
head. The pipe must be disconnected from the cylinder head before head removal.

Secondary Air Pump

The Secondary Air Pump compresses the fresh air which enters the pump from the bottom side
through a non-serviceable air filter. The performance of the pump is monitored by a pressure sensor
located in the top of the left hand combination valve. This check also monitors the performance of
the solenoid valves and their ability to close off the passage to the reed valves.
* Refer to STIS (Subaru Technical Infromation System) *** New Feature
July 2006
2007 Legacy Page 67