| The secondary air system is designed to enable the catalytic converter to heat up and reach its operating temperature more quickly after a cold start. |
| Because of the over-enrichment of the mixture in the cold start phase, the proportion of unburned hydrocarbons in the exhaust gas is higher. The secondary air system improves the afterburning (oxidation) process in the catalytic converter, and thus reduces toxic emissions. The heat generated by oxidisation accelerates the “light off” of the catalytic converter and significantly improves exhaust gas quality during warm-up. |
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| In the warm-up phase, the engine control unit activates the secondary air pump via the secondary air pump relay. Air is routed to the secondary air combination valve. |
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| In parallel to this, the secondary air inlet valve is activated and allows vacuum to pass to the secondary air combination valve. In this way, the combination valve opens a passage for the secondary air system to supply air to the exhaust ports in the cylinder head. |
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