Secondary Air Injection (Air) Valve, Checking

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

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

Test requirements
- The Secondary Air Injection (AIR) Solenoid Valve -N112- fuse OK.
- The Fuel Pump (FP) Relay J17 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. Service and Repair

Start diagnosis

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 - 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:

Checking wiring
If the manufacturers test box is being used. Perform the following step.
- Install the test box Test Box 105 Pin VAG1598/31.
If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220. Service and Repair






- Using a multimeter, check the Secondary Air Injection (AIR) Solenoid Valve N112 electrical harness connector terminal 2 to the Motronic Control Module (ECM) J220 electrical harness connector T121 terminal 9 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, lose or broken terminals.
- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring:
- Erase the DTC memory. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Perform a road test to verify repair.
If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- End diagnosis.
If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the MFI Engine Control Module (ECM) J220. Service and Repair
- Assembly is performed in the reverse of the removal.

Final procedures
After repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

End diagnosis