Low Secondary Air Flow -- Manual Transmission Only

NAME OF CODE:
Low Secondary Air Flow

WHEN MONITORED:
After engine start-up at idle. The secondary air monitor feature performs a functional and flow rate test of the secondary air system by monitoring the response of the dual O2 system with the air system active and inactive.

SET CONDITION:
The PCM does not see a calibrated amount of change in the dual O2 system for a calibrated amount of tests.

THEORY OF OPERATION:
The secondary air solenoid allows the air aspirator system to be turned ON for a period of time after start up. This system contains an air shut-off solenoid in line between the air cleaner and the aspirator valve. The air shut-off valve is a vacuum actuated diaphragm valve with an electric solenoid to control vacuum supplied to the diaphragm valve. An aspirator valve utilizes exhaust pressure pulsation to draw air into the exhaust system reducing carbon monoxide and hydrocarbon emissions. The system draws fresh air through the air cleaner and passes it through either a steel reed valve or a loaded one-way rubber diaphragm.

POSSIBLE CAUSES:
- Aspirator valve failure
- Leaking exhaust system
- Solenoid failure
- Broken or collapsed hoses and tubes