Secondary Air Injection (AIR) Solenoid Valve-N112- Checking

Secondary Air Injection (AIR) Solenoid Valve -N112-, Checking

Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.

Test requirements
- Fuse S234 OK.
- The Fuel Pump (FP) Relay J17 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.

Procedure

NOTE: Voltage is supplied to the Secondary Air Injection (AIR) Solenoid Valve N112 from the Fuel Pump (FP) Relay J17 .

Procedure







- Disconnect the Secondary Air Injection (AIR) Solenoid Valve N112 electrical harness connector - 2 - .

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 degrees 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

Crank the engine.







- 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 Fuel Pump (FP) Relay J17 terminal 2 for a short circuit to Battery positive (+), Ground (GND), or an open circuit.
- Check the electrical harness connector for damage, corrosion, lose 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 test box.

If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220.







- Using a multimeter , check the Secondary Air Injection (AIR) Solenoid Valve N112 electrical harness connector terminal 2 to the Motronic Engine Control Module (ECM) J220 electrical harness connector terminal 9 for an open circuit.

Secondary Air Injection (AIR) Motronic Engine Control Module
Solenoid Valve N112 electrical (ECM) J220 electrical connector
harness connector terminal terminal or test box socket
2 9

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, lose 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) J220.

Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code.

- End of diagnosis.





With Manufacturers Scan Tool

Secondary Air Injection (AIR) Solenoid Valve N112 , Checking







Special tools, testers and auxiliary items required
- Multimeter VAG1526A or equivalent
- Voltage tester VAG1527B
- Connector test set VAG1594A
- Adapter VAG1598/31
- Vehicle Diagnostic, Testing and Information System VAS5051 VAS5051 with VAS5051/1
or
- Scan Tool VAG1551 with VAG1551/3A

Requirement
- Vehicle Diagnostic, Testing and Information System VAS5051 or Scan Tool VAG1551 must be connected.

Work sequence

NOTE: The Secondary Air Injection (AIR) solenoid valve N112 and its wiring are monitored by the engine control module.

- Read DTC memory of engine control module.

If display shows a DTC relating to secondary Air Injection (AIR) solenoid valve N112 :







- Disconnect hoses from secondary Air Injection (AIR) solenoid valve N112 - 2 - , but leave electrical connector connected.
- Installation location: under intake manifold

NOTE: Illustration shows removed intake manifold viewed from below.







- Connect test hose to valve connection marked with an - arrow - .
- Start output Diagnostic Test Mode and actuate Secondary Air Injection (AIR) solenoid valve N112.

Indicated on display

Output Diagnostic Test Mode ->
Secondary Air Injection solenoid valve -N112

- Valve must click...
- ...and must open and close (can be checked by blowing into test hose).

If valve does not click:
- Check internal resistance of valve.

If valve does not open or close properly:
- Replace Secondary Air Injection (AIR) solenoid valve N112 .

Checking internal resistance







- Disconnect connector at Secondary Air Injection (AIR) solenoid valve N112 - 2 -.







- Connect multimeter and measure resistance at valve.
- Specification: 27 to 30 Ohms

If reading does not match specification:
- Replace Secondary Air Injection (AIR) solenoid valve N112 .

If measured value matches specification:
- Check power supply.

Checking power supply

NOTE: Secondary Air Injection (AIR) solenoid valve N112 is supplied with power via fuel pump relay.

Requirements

- Fuse for secondary air injection solenoid valve OK
- Fuel pump relay OK
- Disconnect connector at valve.







- Connect voltage tester VAG1527B as follows:

Connector contact Measure to
1 Engine Ground

- Briefly operate starter.
- LED must light up

If LED does not light up:
- Check for open circuit in wiring from contact 1 of connector through fuse to fuel pump relay.
- If necessary, eliminate open circuit.

If LED lights up:
- Check actuation.

Checking actuation







- Connect voltage tester VAG1527B to contact 1 (positive) and 2 of connector.
- Start output Diagnostic Test Mode and actuate Secondary Air Injection (AIR) solenoid valve N112 .
- LED must flash

If LED does not flash or if it is permanently lit:
- Connect test box VAG1598/31 to engine control module wiring harness. Engine control module must not be connected.







- Check for open circuit and short to Ground/positive in following wiring connection:

Connector contact Test box VAG1598/31 socket
2 9

- If necessary, eliminate open circuit/short circuit.

If wiring is OK:
- Replace engine control module.