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 system injects air into the exhaust port of the cylinder head using an electric air pump, starting when the engine is started cold and operating until the catalyst warms up, in order to promote combustion of unburned fuel and decrease the amount of hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas.

A003CYTE13
DTC No. DTC Detection Condition Trouble Area
P0412

  • After cold engine starts, all of following conditions are met (1 trip detection logic):


    1. Secondary air injection system not operating (air pump OFF, 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 drive circuit

  • Short between air switching valve drive circuit and +B circuit

  • Air injection control driver

  • Air switching valve assembly

  • ECM
P0412

  • After cold engine starts, all of following conditions are met (1 trip detection logic):


    1. Secondary air injection system operating (air pump ON, 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 drive circuit and body ground

  • Air injection control driver

  • Air switching valve assembly

  • ECM

MONITOR DESCRIPTION

The Air Injection Control Driver (AID) detects open and short circuits according to the voltages of the air pump terminal and the Air Switching Valve (ASV) terminal, and transmits diagnostic information as a signal to the ECM.

For a short time after cold engine starts, the ECM transmits command signals to the AID to drive the air pump and ASV.

The AID transmits an ASV malfunction signal to the ECM if either of the following conditions is met:


The ECM sets the DTC based on diagnostic signals from the AID.

WIRING DIAGRAM

A003GNUE02

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE


  1. INSPECT AIR SWITCHING VALVE ASSEMBLY


    1. Inspect the air switching valve assembly Click here.


    NG

    REPLACE AIR SWITCHING VALVE ASSEMBLY Click here

    OK

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


    1. Disconnect the air switching valve connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D30-1 - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the air switching valve connector.

    2. Disconnect the air injection control driver connector.

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

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR INJECTION CONTROL DRIVER