Secondary Air Injection

PRINCIPLE OF OPERATION, SECONDARY AIR INJECTION (Certain engine versions in certain markets)





The secondary air injection system consists of a secondary air injection pump which blows air into the exhaust manifold via a vacuum-controlled valve. The purpose is to start the catalytic converter working as quickly as possible after starting from cold.

The additional air starts a chemical process using burnt and partially burnt fuel (HC and CO), thus generating heat.

The pump relay is supplied with current from the main relay and grounded via pin 52 of the control module. The same lead is connected to pin 37 of the control module. By measuring the voltage on pin 37, the control module determines whether the circuit is electrically correct.

The function is activated when the engine is started if the following conditions are fulfilled:

- Coolant temperature 5 - 35°C
- Intake air temperature 5 - 35°C
- Engine speed <4000 rpm

The function is activated for 60 seconds.