Code No. P0428: No. 2 Exhaust Gas Temperature Sensor (Catalyst Temperature) Circuit High Input


OPERATION



  • A power voltage of 5 V is applied to the No. 2 exhaust gas temperature sensor (catalyst temperature) output terminal from the engine-ECU connector terminal DTS2.
  • The power voltage is earthed to the engine-ECU connector terminal DT2E from the No. 2 exhaust gas temperature sensor (catalyst temperature) connector terminal.

FUNCTION



  • The No. 2 exhaust gas temperature sensor (catalyst temperature) converts the catalyst temperature into a voltage and inputs the voltage signal to the engine-ECU.
  • Engine-ECU uses this voltage for DPF regeneration control.
  • The No. 2 exhaust gas temperature sensor (catalyst temperature) is a kind of resistor, which has characteristics to reduce its resistance as the catalyst temperature rises. Therefore, the sensor output voltage varies with the catalyst temperature, and becomes lower as the catalyst temperature rises.

TROUBLE JUDGMENT


Check Conditions
  • Battery positive voltage is 8 - 16 V.
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
  • Vehicle speed is 20 km/h or higher.
Judgment Criterion
  • The No. 2 exhaust gas temperature sensor (catalyst temperature) output voltage is 4.95 V or more.

FAIL-SAFE AND BACKUP FUNCTION



  • The throttle valve is opened (Electrical discontinuity).
  • The EGR control is stopped (fully closed).
  • The DPF regeneration is prohibited.
  • The AS&G control is prohibited.

PROBABLE CAUSES



  • Failed No. 2 exhaust gas temperature sensor (catalyst temperature)
  • Open circuit or harness damage in No. 2 exhaust gas temperature sensor (catalyst temperature) circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III data list

  • Refer to Data List Reference Table

  1. Item 118: No. 2 exhaust gas temperature sensor (catalyst temperature)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2.

STEP 2. Check No. 2 exhaust gas temperature sensor (catalyst temperature) itself.

  • No. 2 exhaust gas temperature sensor (catalyst temperature) connector check.
  • Check No. 2 exhaust gas temperature sensor (catalyst temperature) itself (Refer to GROUP 17 - Emission Control <DIESEL> - Diesel Particulate Filter (DPF) System - No. 2 Exhaust Gas Temperature Sensor (catalyst temperature) Check ).

Q. Is the check result normal?
Go to Step 3.
Repair or replace the connector, or replace the No. 2 exhaust gas temperature sensor (catalyst temperature). After replacing the No. 2 exhaust gas temperature sensor (catalyst temperature), carry out the forcible DPF regeneration. (Refer to GROUP 17 - Emission Control <DIESEL> - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).

STEP 3. Perform voltage measurement at No. 2 exhaust gas temperature sensor (catalyst temperature) connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal engine-ECU DTS2 line and body earth.
OK: 4.5 - 4.9 V

Q. Is the check result normal?
Go to Step 6.
Go to Step 4.

STEP 4. Check harness between No. 2 exhaust gas temperature sensor (catalyst temperature) connector terminal and engine-ECU connector terminal DTS2.

  • Check output line for open circuit.

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.

STEP 5. M.U.T.-III data list

  • Refer to Data List Reference Table

  1. Item 118: No. 2 exhaust gas temperature sensor (catalyst temperature)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.

STEP 6. Perform resistance measurement at No. 2 exhaust gas temperature sensor (catalyst temperature) connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal engine-ECU DT2E line and body earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?
Go to Step 8.
Go to Step 7.

STEP 7. Check harness between No. 2 exhaust gas temperature sensor (catalyst temperature) connector terminal and engine-ECU connector terminal DT2E.

  • Check earthing line for open circuit and damage.

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.

STEP 8. Check harness between No. 2 exhaust gas temperature sensor (catalyst temperature) connector terminal and engine-ECU connector terminal DTS2.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.