Secondary Air Injection Solenoid Valve, Checking

Special Tools And Workshop Equipment Required 

• Multimeter
• Wiring diagram.

Test Requirements 

• The Secondary Air Injection (AIR) Solenoid Valve --N112-- fuse OK.
• The Motronic Engine Control Module (ECM) Power Supply Relay -J271- fuse OK.
• Battery voltage at least 12.5 V.
• All electrical consumers switched off (radiator fan must NOT run during test).
• A/C switched off.
• The ignition switched off.

Test Procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .

Start Diagnosis 

Procedure 

-- Disconnect the Secondary Air Injection (AIR) Solenoid Valve -N112- electrical harness connector -1-.

Checking internal resistance 

-- Using a multimeter, check the Secondary Air Injection (AIR) Solenoid Valve -N112- terminals 1 to 2 for resistance.

Specified Value: 25 to 35 Ω (At Approx. 20 °C)

If the specified value was Not obtained:

-- Replace the Secondary Air Injection (AIR) Solenoid Valve -N112-.

If the specified value was obtained:

Checking voltage supply 

Switch the ignition on.

-- Using a multimeter, check the Secondary Air Injection (AIR) Solenoid Valve -N112- electrical connector terminal 1 to Ground (GND) for voltage.

Specified Value: Battery Voltage.

Switch the ignition off.

If the specified value was not obtained:

-- Check the wiring from the Secondary Air Injection (AIR) Solenoid Valve N112 electrical connector terminal 1 to the Secondary Air Injection (AIR) Pump Relay J299 terminal 86/1 for a short circuit to Ground (GND), or an open circuit.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking wiring 

If the manufacturers test box is being used. Perform the following step.

-- Install the Adapter Cable (121 Pin) VAG1598/31 .

If the manufacturers test box is not being used. Perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to the Repair Information.

-- Using a multimeter , check the Secondary Air Injection (AIR) Solenoid Valve N112 electrical harness connector terminal 2 to the Motronic Engine Control Module (ECM) J623 electrical harness connector T121 terminal 121 for an open circuit.

Secondary Air Injection (AIR) Solenoid Valve -N112- electrical harness connector terminal	Motronic Engine Control Module (ECM) J623 electrical connector T121 terminal or test box socket
2	121

Specified Value: 1.5 Ω Max. 

If the specified value was not obtained:

-- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to the Repair Information.

Final Procedures 

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .

End of Diagnosis.