The secondary air injection (AIR) system helps reduce hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) exhaust emissions. It also helps to warm up the 3-way catalytic converters quickly on engine start-up so conversion of exhaust gases may occur sooner.
The system includes the following components:
The AIR pump and solenoid is controlled by the PCM. The PCM turns ON the AIR pump by providing the ground to complete the circuit which energizes the AIR pump solenoid relay. When air to the exhaust ports is desired, the PCM energizes the relay in order to turn ON the solenoid and the AIR pump.
The PCM turns ON the AIR pump during startup any time the engine coolant temperature is above 0°C (32°F). The AIR pump operates for a maximum of 240 seconds, or until the system enters Closed Loop operation. When the PCM commands the AIR pump solenoid relay OFF, the AIR pump stops and the solenoid turns OFF, stopping vacuum to the shut off valve. The shut off valve closes in order to prevent any air getting to the exhaust ports.
The AIR system is disabled under the following conditions:
If no air, oxygen, flow enters the exhaust stream at the exhaust ports. The HC and CO emission levels are too high.
Air flowing to the exhaust ports at all times could increase temperature of the 3-way catalytic converter.
The diagnostic trouble codes P0410, P0418, P1415, and P1416 set if there is a malfunction in the following components:
The AIR pump is an electric type pump which requires no periodic maintenance.
The engine should be at normal operating temperature in neutral at idle. Using the scan tool enable the AIR pump system. Select heated oxygen sensors (HO2S) voltages for both bank 1 and bank 2 HO2S. The HO2S voltages for both sensors should remain under 350 mV because air is being directed to the exhaust ports. If the HO2S voltages remain low during the Output Test, the AIR pump, solenoid and shut off valve are operating satisfactorily. If the HO2S voltage does not remain low when the AIR pump is enabled, inspect for the following:
The AIR solenoid is an electrically operated solenoid. The solenoid is activated in conjunction with the AIR pump by the AIR pump solenoid relay. Intake manifold vacuum is then allowed through the solenoid to the shut off valve. The solenoid mounting bracket has a locating tab to ensure proper alignment of the solenoid on the base.
The shut-off valve is a vacuum operated valve. Vacuum is allowed to the vacuum port by the solenoid. The vacuum opens the valve and allows air from the air pump into the inlet port, through the valve and then through the outlet port to the hoses and pipes.
If a leak is suspected on the pressure side of the system, or if a hose or pipe has been disconnected on the pressure side, the connections should be checked for leaks with a soapy water solution. With the AIR pump running, bubbles form if a leak exists.
Caution: Allow the check valve to cool off before proceeding with the next check in order to avoid being burned. Tap on the check valve in order to remove any debris that may be inside the valve.
A check valve should be inspected whenever the hose is disconnected or whenever check valve failure is suspected. An AIR pump that had become inoperative and had shown indications of having exhaust gases in the outlet port would indicate check valve failure.
