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: 3.5-8.5 Ω (at approx. 20° C)

If the specified value was Not obtained:

-- Replace the Secondary Air Injection (AIR) Solenoid Valve -N112-. Refer to the Repair Manual.

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 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- terminal 1 to fuse 24 in Fuse Panel B for a short circuit to Ground, or an open circuit.

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

-- If necessary, repair the wiring connection.

If the specified value was obtained:

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 Manual.

-- Using a multimeter --, check the Secondary Air Injection (AIR) Solenoid Valve -N112- electrical harness connector to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T60 for an open circuit.

Secondary Air Injection (AIR) Solenoid Valve -N112- electrical harness connector terminal	Motronic Engine Control Module (ECM) -J623- electrical connector T60 terminal or test box socket
2	17

Specified value: 1.5 Ω Max.

If the specified value was Not obtained:

-- Check the wiring for an open, high resistance or short to ground.

-- 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 Manual.

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 .