SFI SYSTEM (w/ Secondary Air Injection System), Diagnostic DTC:P0418

DTC Code DTC Name
P0418 Secondary Air Injection System Control "A" Circuit

DESCRIPTION

Refer to DTC P0412 Click here.

DTC No. DTC Detection Condition Trouble Area
P0418

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

    (1 trip detection logic):


    1. Air Injection (AI) system not operate (air pump OFF, Air Switch Valve (ASV) OFF)

    2. Diagnostic signal from Air Injection Control Driver (AID) 20 %

    3. Battery voltage 8 V or more

  • Open in air pump drive circuit

  • Short between air pump circuit and +B circuit

  • Air pump

  • Air injection control driver

  • ECM

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

    (1 trip detection logic):


    1. While Air Injection (AI) system operating (air pump ON, Air Switching Valve (ASV) ON)

    2. Diagnostic signal from Air Injection Control Driver (AID) 20%

    3. Battery voltage 8 V or more

  • Short between air pump circuit and body ground

  • Air pump

  • Air injection control driver

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

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

WIRING DIAGRAM

Refer to DTC P0412 Click here.

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. CHECK HARNESS AND CONNECTOR (AIR PUMP ASSEMBLY - BODY GROUND)


    1. A01BHG7E01

      Disconnect the B17 air pump connector.

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

      Resistance
      Tester Connection Specified Condition
      Air pump (B17-1) - Body ground Below 1 Ω

    3. Reconnect the air pump connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (AIR PUMP ASSEMBLY - AIR INJECTION CONTROL DRIVER)


    1. A01BDXQE02

      Disconnect the B14 Air Injection Control Driver (AID) connector.

    2. Disconnect the B17 air pump connector.

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

      Resistance
      Tester Connection Specified Condition
      Air pump (B17-2) - VP (B14-2) Below 1 Ω
      Air pump (B17-2) or VP (B14-2) - Body Ground 10 kΩ or higher

    4. Reconnect the air pump connector.

    5. Reconnect the AID connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. INSPECT AIR PUMP ASSEMBLY


    1. Connect the intelligent tester to the DLC3.

    2. A01BCLEE01

      Connect the 400 A probe of an ammeter to the (+) wire of the air pump.

    3. Turn the ignition switch to ON and turn the tester ON.

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

    5. Cool the engine down until the engine coolant temperature and the ambient temperature are almost the same.

    6. Crank the engine and measure the current when the air pump is on and off.

      Standard Current
      AI System (Air Pump) Operation Specified Condition

      ON

      (soon after the cold engine starts)

      		 10 to 40 A

      OFF

      (engine is idling)

      		 Below 1 A

      Tech Tips

      Check whether the air pump operating sound occurs when the AI system operates (soon after cold engine starts). If the air pump operating sound is not confirmed, the pump may be defective.


    NG

    REPLACE AIR PUMP ASSEMBLY Click here

    OK

    REPLACE AIR INJECTION CONTROL DRIVER

  4. REPLACE AIR PUMP ASSEMBLY


    1. Replace the air pump assembly Click here.


    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC P0418)


    1. Cool the engine down until the engine coolant temperature and the ambient temperature are almost the same.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON and 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. Start the engine and confirm that the AI system has been operated.

    6. Enter the following menus: Powertrain / Engine and ECT / DTC.

    7. Read DTCs.

      OK
      No DTC output.

    NG

    REPLACE AIR INJECTION CONTROL DRIVER

    OK

    END