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Home >> Mercedes Benz >> 1981 >> 280E >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Air Injection System >> Operation >> 380 Models

380 Models

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The air injection system is used to improve catalyst operation when the engine is warming up. Air is injected only if engine coolant temperature is below 108° F (42° C), oil temperature is above 61° F (18° C) and the oxygen sensor is not operating. When these conditions are present, the air injection relay provides power to the air pump clutch and the switch-over valve.

When the switch-over valve is activated, it provides vacuum to open the air injection shut-off valve, allowing air from the pump to pass through the check valve into the exhaust manifold.