The secondary air system serves as an exhaust gas treatment during the engine warm-up phase thus enabling the catalytic converter to reach its operating temperature faster.
The vane pump used in the secondary air system is driven mechanically by a V-belt. The mounting bracket for the air pump is secured on the A/C compressor. Air is injected via hoses and lines in a longitudinal channel in the cylinder head and from here into the exhaust ports.
Two non-return valves and a shut-off valve prevent exhaust gas flowing back to the air pump. The pneumatically operated shut-off valve is activated with an electric changeover valve. A magnetic clutch cuts in the system as required. The operating time depends on the engine temperature, load and speed.