Air Injection Vacuum Control Solenoid Valve: Testing and Inspection

Secondary Air Injection Solenoid Valve, Checking

Special tools, testers and auxiliary items 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 ] Preliminary Check.

Start diagnosis

• Voltage is supplied to the Secondary Air Injection (AIR) Solenoid Valve (N112) from the Motronic Engine Control Module (ECM) Power Supply Relay (J271).

Procedure

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





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 ohms (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 => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.

- 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.









Specified value: 1.5 ohms Max.

If the specification 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) => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.

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 ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code, Setting ] Readiness Code, Setting.

End of Diagnosis.