Code No. P0427: No. 2 Exhaust Gas Temperature Sensor (catalyst temperature) Circuit Low Input <Euro5b>




OPERATION



  • A power voltage of 5 V is applied to the No. 2 exhaust gas temperature sensor (catalyst temperature) output terminal (terminal No. 1) from the engine-ECU (terminal No. 59).
  • The power voltage is earthed to the engine-ECU (terminal No. 83) from the No. 2 exhaust gas temperature sensor (catalyst temperature) (terminal No. 2).

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 output 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.
Judgment Criterion
  • The No. 2 exhaust gas temperature sensor (catalyst temperature) output voltage is 0.255 V or less.

PROBABLE CAUSES



  • Failed No. 2 exhaust gas temperature sensor (catalyst temperature)
  • Short circuit 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. Connector check: A-159 No. 2 exhaust gas temperature sensor (catalyst temperature) connector

Q. Is the check result normal?

Go to Step 3.

Repair or replace the connector.

STEP 3. Check No. 2 exhaust gas temperature sensor (catalyst temperature) itself.

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

Q. Is the check result normal?
Go to Step 4.
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 Particulate Filter (DPF) System - Forcible DPF Regeneration ).

STEP 4. Connector check: C-105 engine-ECU connector

Q. Is the check result normal?

Go to Step 5.

Repair or replace the connector.

STEP 5. Check harness between A-159 (terminal No. 1) No. 2 exhaust gas temperature sensor (catalyst temperature) connector and C-105 (terminal No. 59) engine-ECU connector.


note Before checking harness, check intermediate connector A-28, and repair if necessary.

  • Check output line for short circuit.

Q. Is the check result normal?

Go to Step 6.

Repair the damaged harness wire.

STEP 6. 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. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, carry out the forcible DPF regeneration. (Refer to GROUP 17 - Emission Control - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).