SFI SYSTEM (w/ Secondary Air Injection System), Diagnostic DTC:P0412

DTC Code DTC Name
P0412 Secondary Air Injection System Switching Valve "A" Circuit

DESCRIPTION

The Secondary Air Injection (AI) system consists of an air pump, Air Switching Valve (ASV), Air Injection Control Driver (AID) and the ECM. After the cold engine starts, the AI system pumps the secondary air to the exhaust port of the cylinder head to purify the exhaust emissions.

The ECM transmits command signals to the AID to drive the ASV and the air pump, and the AID drives them.

The function of AID is not only pump and valve driving, but also diagnosis function to detect malfunctions in the AI system circuit.

Tech Tips

A large amount of current is required to drive the air pump and ASV so that an air injection control driver is provided newly on the previous system.

A01BD6YE01
DTC No. DTC Detection Conditions Trouble Areas
P0412

  • After cold engine starts, all of following conditions are met

    (1 trip detection logic):


    1. Air Injection System not operate (air pump OFF and air switching valve OFF)

    2. Diagnostic signal from air injection control driver 40 %

    3. Battery voltage 8 V or more

  • Open in air switching valve circuit and +B circuit

  • Air injection control driver

  • Air switching valve

  • ECM
P0412

  • After cold engine starts, all of following conditions are met

    (1 trip detection logic):


    1. While Air Injection System operating (air pump ON and air switching valve ON)

    2. Diagnostic signal from air injection control driver 40 %

    3. Battery voltage 8 V or more

  • Short between air switching valve circuit and body ground

  • Air injection control driver

  • Air switching valve

  • ECM

MONITOR DESCRIPTION

Air Injection Control Driver (AID) detects an open or short in the air pump and Air Switching Valve (ASV) circuit according to the terminal voltage and sends a signal as the diagnostic information to the ECM.

After a cold engine start, the ECM transmits command signals to the AID to drive the air pump and ASV.

The AID outputs the air switching valve malfunction signal to the ECM if: 1) the voltage at the AID terminal relating to the ASV is low despite the AID receiving command signals from the ECM to drive the ASV or 2) the voltage at the AID terminal relating to the ASV is high despite the AID receiving no command signals from the ECM to drive the ASV.

The ECM sets the DTC based on the diagnostic signal from the Air Injection Driver.

WIRING DIAGRAM

A01BBQXE02

INSPECTION PROCEDURE

Tech Tips

The diagnostic information output from the Air Injection Control Driver (AID) can be confirmed by connecting an oscilloscope to the diagnostic information terminal of the AID.


  1. A01BBIVE06

    Connect the intelligent tester to the DLC3.

  2. Connect an oscilloscope probe to the AIDI terminal of the ECM.

  3. Turn the tester ON.

  4. Enter the following menus: Powertrain / Engine and ECT / Data List / Secondary Air Control VSV and 2nd Air System Status.

  5. Monitor the voltage output of the AID (duty ratio signal) when the AI system operates and does not operate.

    Tech Tips

    Since the AI system pumps secondary air to the exhaust port of the cylinder head for a short time after a cold engine start, if the AI system does not operate, cool the engine down until the engine coolant temperature and the ambient air temperature are almost the same.

    Oscilloscope range:
    Items Contents
    Terminals CH1: AIDI (D3-20) - E1 (D1-3)
    Equipment Settings 5 V/Division, 20 to 40 ms/Division
    Conditions Idling
    A01BC2DE02
    A01BGJ4E02

Tech Tips

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE


  1. INSPECT AIR SWITCHING VALVE ASSEMBLY


    1. A01BDLAE01

      Disconnect the D30 Air Switching Valve (ASV) connector.

    2. Measure the resistance according to the value(s) in the table below.

      Resistance
      Tester Connection Specified Condition
      E (D30-1) - VV (D30-2) 4.5 to 5.5 Ω

    3. Reconnect the ASV connector.


    NG

    REPLACE AIR SWITCHING VALVE ASSEMBLY

    OK

  2. CHECK HARNESS AND CONNECTOR (AIR SWITCHING VALVE ASSEMBLY - BODY GROUND)


    1. A01BD0NE01

      Disconnect the D30 ASV connector.

    2. Measure the resistance according to the value(s) in the table below.

      Resistance
      Tester Connection Specified Condition
      E (D30-1) - Body ground Below 1 Ω

    3. Reconnect the ASV connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (AIR SWITCHING VALVE ASSEMBLY - AIR INJECTION CONTROL DRIVER)


    1. A01BD83E01

      Disconnect the D30 ASV connector.

    2. Disconnect the B12 Air Injection Control Driver (AID) connector.

    3. Measure the resistance according to the value(s) in the table below.

      Resistance
      Tester Connection Specified Condition
      VV (D30-2) - VV (B12-6) Below 1 Ω
      VV (D30-2) or VV (B12-6) - Body ground 10 kΩ or higher

    4. Reconnect the ASV connector.

    5. Reconnect the AID connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR INJECTION CONTROL DRIVER