Secondary Air System

Secondary Air System MSS65

Functional description, see BMW Service Technology:
TIS -> Document -> SI Technology -> Enter SBT Number
SBT number:
- 11 04 04 097

Overview of functions
After engine start, the secondary air system mixes fresh air in the emission to reduce the proportion of hydrocarbons in the emissions.

The secondary air pump is activated by the DME via a relay and ensures the necessary fresh-air supply. Activation of the relay is monitored by the DME.

The secondary air valves are located on the exhaust manifolds and they open when the secondary air pump is running due to the pressure created by the pump. The secondary air valves are not activated by the DME.

The secondary air flow sensor monitors the system; this is located downstream of the secondary air pump in the main line. The secondary air flow sensor monitored by the DME.