The secondary air injection (AIR) system helps reduce exhaust
emissions. The system forces fresh filtered air into the exhaust stream in
order to accelerate the catalyst operation.
The system includes the following components:
| • | The AIR pump --The AIR pump supplies filtered air through
the secondary air injection system into the exhaust stream. The control module
provides ground for the pump relay, then the battery voltage is applied to
the pump. The filter is the only serviceable part of the pump. |
| • | The AIR vacuum control solenoid --The AIR vacuum control
solenoid controls the AIR Shut OFF Valve. When the secondary air injection
system is enabled, the control module provides a ground to the solenoid. Enabling
the solenoid allows the engine vacuum to be applied to the AIR shut off valve. |
| • | The AIR shut off valve--The AIR shut off valve is vacuum
operated. When the secondary air injection system is enabled, vacuum is applied
to the valve. The vacuum opens the valve, and allows air from the AIR Pump
to flow to the check valves. |
| • | The check valves--The check valves prevent back flow of the
exhaust gases into the secondary air injection system. An inoperative AIR
pump that had shown indications of exhaust gases in the outlet port would
indicate a check valve failure. |
| • | The plumbing --The plumbing carries the air from the pump
to the exhaust stream. The plumbing includes the hoses, the pipes, and the
clamps. You can test the plumbing for leaks using a soapy water solution.
With the AIR pump running, the bubbles with form if a leak exists. |
Results of Incorrect Operation
If no air flow enters the exhaust stream, the start-up emission levels
will rise. The control module can detect a system flow problem using the pre-catalyst
HO2S and the short term fuel trim. If a system flow problem exists, the HO2S
voltage will not indicate an expected lean condition. The short term fuel
trim will not increase, and a DTC will set.
If incorrect voltage is present on the vacuum control solenoid or on
the pump relay control circuits, the device will not operate. The control
module will detect this condition, and a DTC will set.
If a secondary air injection fault is detected. the following
DTCs can set:
| • | P0410--A system flow problem has been detected. |
| • | P0412--A vacuum control solenoid control circuit problem
has been detected. |
| • | P0418--A pump relay control circuit problem has been detected. |
| • | P1415--A Bank 1 flow problem has been detected. |
| • | P1416--A Bank 2 flow problem has been detected. |
