Air Injection: Service and Repair

Secondary air system

WARNING!
When doing any repair work, especially in the engine compartment, due to the cramped conditions, pay affection the following:
^ Route all sorts of pipes (e.g. for fuel, hydraulics, evaporative emissions system coolant refrigerant, brake fluid and vacuum pipes and hoses) and electrical wiring so that the original positions are restored.
^ Make sure sufficient clearance to all moving or hot components.

Function
The secondary air system blows air in behind the exhaust valve for 100 seconds during a cold start (+5° C to +33°C coolant temperature). This produces an oxygen rich exhaust gas, causes an after burn and reduces the heating-up phase of the three way catalytic converter. Activation occurs from the Motronic control module (J220) via the secondary air pump relay (J299) to secondary air intake valve (N112, change-over valve) and combi-valve.

Secondary air system components, removing and installing





Notes:
^ Components marked with an * are checked by the On Board Diagnostic (OBD).
^ Components marked with **are checked by Output Diagnostic Test Mode (DTM).

^ Secondary air pump relay (J299)**.
1-Combivalve
^ Checking
2-Gasket
^ Replace
3-Connection
^ Secured to cylinder head
4-Bracket
5-10 Nm
6-Bracket
^ Secured to intake manifold
7-To vacuum reservoir
8-Vacuum hose
9-Connector
^ 2 pin
10 Secondary
^ air intake valve (N112)*/**
^ Secured to bracket with 6 Nm
^ Resistance: 21 to 24 ohms
^ Checking
11-Intake hose
^ For secondary air pump
^ Make sure seated tightly
^ Press together at front to release
12-To air cleaner
13-O-Ring
^ Replace
14-Connector
^ 2 pin
^ For secondary air pump motor
15-10 Nm
16 Secondary-air pump motor (V101)**
^ Checking function
17-10 Nm
18-Pressure hose
^ Make sure seated tightly
^ Press together at front to release
19-10 Nm
^ Secured to bracket = item 6
20-10 Nm
21-Gasket
^ Replace





Fig. 1 Secondary air pump relay (J299)-arrow
^ If tools are necessary to pull relays or control modules out of the relay plate, first disconnect battery Ground strap.
^ Before disconnecting battery Ground strap obtain code for radios with anti-theft coding.