ECD SYSTEM, Diagnostic DTC:P1426

DTC Code DTC Name
P1426 Differential Pressure Sensor Installation Error

DESCRIPTION

A01CHKKE03

The two sensing chambers of the differential pressure sensor are mounted to monitor the pressure before and after the DPF (*2) catalytic converter. The sensor itself is not located on the engine assembly in order to reduce the influence of vibration. The sensor is a semiconductor-type that is not influenced by exhaust gases.

The ECM compares the exhaust gas pressure before and after DPF catalytic converter by monitoring the pressure using the upstream and downstream sensing chambers of the differential pressure sensor. If the difference between the pressure before and after the catalytic converter exceeds a predetermined level, the ECM judges that the catalytic converter has clogged with particulate matter (PM). When the ECM judges that a partially clogged condition exists, the ECM begins to perform DPF catalyst regeneration.

*2: Diesel Particulate Filter

Tech Tips

If the vacuum hoses of the differential pressure sensor are incorrectly connected (crossed), the ECM interprets this as abnormal pressure difference, DTC P1426 (Differential Pressure Sensor [Installation]) will be set and the MIL will be illuminated.

DTC No. DTC Detection Condition Trouble Area
P1426 Output voltage from the differential pressure sensor indicates positive pressure as negative pressure (and vise versa) (1 trip detection logic)

  • Incorrect arrangement differential pressure sensor hose piping

  • Differential pressure sensor vacuum hose is clogged

  • Blockage in vacuum transmitting pipe sub-assembly

  • Differential pressure sensor

  • ECM

Tech Tips


  • DTC P1425 (Differential pressure sensor circuit), DTC P1427 (Differential pressure sensor circuit low) and/or DTC P1428 (Differential pressure sensor high) will be present if there is an open or short in the differential pressure sensor circuit.

  • After confirming DTC P1426, check the differential pressure by selecting the following menus on the tester: Powertrain / Engine and ECT / Data List / DPF Differential Pressure.

    Result
    Condition Differential Pressure Output Sensor Condition
    Ignition switch in the ON position Approximately 0 kPa Normal
    Always 3 kPa Open or short circuit
    3000 rpm (No engine load) Negative output Incorrect arrangement of hose piping

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P1426)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position.

    3. Turn the tester on.

    4. Enter the following menu items: Powertrain / Engine and ECT / DTC.

    5. Read the DTCs.

      Result
      Display (DTC output) Proceed to
      P1426 A
      P1426 and other DTCs B

      Tech Tips

      If codes other than P1426 are output, perform troubleshooting for those DTCs first.


    B

    GO TO DTC CHART

    A

  2. CHECK CONNECTION OF VACUUM HOSE (DIFFERENTIAL PRESSURE SENSOR - CATALYST CONVERTER)


    1. Check if vacuum hose routing between the differential pressure sensor and the catalyst converter is correct.

    2. Check that there is no exhaust gas leakage between the differential pressure sensor and the catalyst converter.


    NG

    RECONNECT VACUUM HOSE

    OK

  3. CHECK BLOCKAGE OF VACUUM HOSE AND CATALYST CONVERTER

    CAUTION:

    Be careful of being burned by exhaust gases during the following inspection.


    1. Disconnect the vacuum hoses (both upstream and downstream) on the differential pressure sensor.

    2. Start the engine.

    3. Check if there are exhaust gas pulsations from both vacuum hoses during idling.


    NG

    REPLACE CLOGGED PARTS

    OK

  4. READ VALUE USING INTELLIGENT TESTER (DIFFERENTIAL PRESSURE)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position and turn the intelligent tester on.

    3. Enter the following menu items: Powertrain / Engine and ECT / Data List / DPF Differential Pressure.

    4. Check that differential pressure is within the specification below.

      Result
      Condition Differential Pressure Output Sensor Condition
      Ignition switch in the ON position Approximately 0 kPa Normal
      Always -5 kPa or 100 kPa Open or short circuit
      3000 rpm (No engine load) Negative output Incorrect arrangement of hose piping

    OK

    CHECK FOR INTERMITTENT PROBLEMS

    NG

    REPLACE DIFFERENTIAL PRESSURE SENSOR ASSEMBLY