SFI 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.

B001VZRE06
DTC No. DTC Detection Condition Trouble Area
P0412

All conditions are met for 3 seconds or more while idling immediately after the engine is started (1 trip detection logic):


  • Secondary air injection system is not operating (the air pump and emission control valve are off).

  • Diagnostic signal from the air injection control driver has a duty cycle of 40% (this indicates an open in the emission control valve circuit).

  • Battery voltage is 8 V or higher.

  • Open in emission control valve drive circuit

  • Air injection control driver assembly

  • No. 1 emission control valve set

  • ECM
P0412

All conditions are met for 3 seconds or more while idling immediately after the engine is started (1 trip detection logic):


  • Secondary air injection system is operating (the air pump and emission control valve are on).

  • Diagnostic signal from the air injection control driver has a duty cycle of 40% (this indicates a short in the emission control valve circuit).

  • Battery voltage is 8 V or higher.

  • Short between emission control valve drive circuit and body ground

  • Air injection control driver assembly

  • No. 1 emission control valve set

  • ECM

MONITOR DESCRIPTION

This DTC indicates an open or short circuit in the circuit containing the emission control valve of the secondary air injection system. The air injection control driver performs diagnosis of the air pump assembly, emission control valve set and itself, and sends the results of this diagnosis to the ECM as a duty signal. When the ECM receives a signal indicating a malfunction in the air pump, emission control valve set or air injection control driver, it illuminates the MIL and stores a DTC.

WIRING DIAGRAM

B001XLWE02

CAUTION / NOTICE / HINT

Tech Tips


  • By using the GTS to perform the Secondary Air Injection Check operation in the System Check, the air-fuel ratio and the pressure in the secondary air injection system passage can be checked while the secondary air injection system is operating. This helps technicians to troubleshoot the system when it malfunctions.

  • Read freeze frame data using the GTS. 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 NO. 1 EMISSION CONTROL VALVE SET


    1. Inspect the No. 1 emission control valve set Click here.


    NG

    REPLACE NO. 1 EMISSION CONTROL VALVE SET Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (NO. 1 EMISSION CONTROL VALVE SET - BODY GROUND)


    1. Disconnect the No. 1 emission control valve set connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C137-1 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (NO. 1 EMISSION CONTROL VALVE SET - AIR INJECTION CONTROL DRIVER ASSEMBLY)


    1. Disconnect the No. 1 emission control valve set connector.

    2. Disconnect the air injection control driver assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C137-5 (+B) - C61-6 (VV) Always Below 1 Ω
      C137-5 (+B) or C61-6 (VV) - Body ground Always 10 kΩ or higher

    OK

    REPLACE AIR INJECTION CONTROL DRIVER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR