ECD SYSTEM, Diagnostic DTC:U029D

DTC Code DTC Name
U029D Lost Communication with NOx Sensor "A"

DESCRIPTION

The ECM sends and receives data to and from the nitrogen oxides sensor via local CAN communication.

U029D
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Turn the ignition switch to ON and wait for 1.6 seconds or more. Communication stops between the ECM and the nitrogen oxides sensor for 1.6 seconds or more.

  • Nitrogen oxides sensor

  • Harness or connector

  • ECM

MONITOR DESCRIPTION

The ECM stores a DTC when a communication malfunction occurs between the nitrogen oxides sensor and ECM.

WIRING DIAGRAM

B007RE5E01

INSPECTION PROCEDURE

Note

Inspect the fuses of circuits related to this system before performing the following inspection procedure.

Tech Tips

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, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK DTC OUTPUT


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. According to the display on the GTS, select "Health Check".

    4. Check for currently output system DTCs.

      Result
      Result Proceed to
      DTC U029D is output A
      DTC U029D and other DTCs are output* B

      Tech Tips

      *If any other DTCs are output, perform troubleshooting for those DTCs first.


    B

    GO TO DTC CHART Click here

    A

  2. CHECK NITROGEN OXIDES SENSOR


    1. Disconnect the nitrogen oxides sensor connector.

    2. Turn the ignition switch to ON.

    3. B007QTEE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Nitrogen oxides sensor)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      r7-5 (BATT) - r7-4 (GND) Ignition switch ON 11 to 14 V

    NG

    INSPECT NOX RELAY Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (NITROGEN OXIDES SENSOR - ECM)


    1. Disconnect the nitrogen oxides sensor connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      r7-2 (CAN+) - B97-41 (CANU) Always Below 1 Ω
      r7-3 (CAN-) - B97-56 (CAND) Always Below 1 Ω
      r7-2 (CAN+) or B97-41 (CANU) - Body ground and other terminals Always 10 kΩ or higher
      r7-3 (CAN-) or B97-56 (CAND) - Body ground and other terminals Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPAIR NITROGEN OXIDES SENSOR


    1. Replace the nitrogen oxides sensor Click here.


    NEXT

  5. CHECK DTC OUTPUT


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. Clear the DTCs.

    4. Turn the ignition switch off for 30 seconds or more.

    5. Turn the ignition switch to ON wait for 1.6 seconds or more.

    6. Turn the GTS on.

    7. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    8. Read the DTCs.

      Result
      Result Proceed to
      No DTC is output A
      DTC U029D is output B

    B

    REPLACE ECM Click here

    A

    END

  6. INSPECT NOX RELAY


    1. Inspect NOX relay Click here.


    NG

    REPLACE NOX PM RELAY

    OK

  7. CHECK HARNESS AND CONNECTOR (NITROGEN OXIDES SENSOR - ENGINE ROOM RELAY BLOCK, BATTERY - ENGINE ROOM RELAY BLOCK)


    1. Disconnect the nitrogen oxides sensor connector.

    2. Remove the NOx PM relay from the engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      r7-5 (BATT) - NOX relay terminal 3 Always Below 1 Ω
      r7-4 (GND) - Body ground Always Below 1 Ω
      NOX relay terminal 1 - Body ground Always Below 1 Ω
      NOX relay terminal 3 or r7-5 (BATT) - Body ground and other terminals Always 10 kΩ or higher

    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      NOX relay terminal 5 - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    GO TO ECM POWER SOURCE CIRCUIT Click here