Code No. P0134: Oxygen Sensor (front) Circuit No Activity Detected


OPERATION



  • Check code No. P0131: oxygen sensor (front) circuit low voltage (Refer to ).
  • Check code No. P0261: No. 1 injector circuit low input (Refer to ).
  • Check code No. P0262: No. 1 injector circuit high input (Refer to ).
  • Check code No. P0264: No. 2 injector circuit low input (Refer to ).
  • Check code No. P0265: No. 2 injector circuit high input (Refer to ).
  • Check code No. P0267: No. 3 injector circuit low input (Refer to ).
  • Check code No. P0268: No. 3 injector circuit high input (Refer to ).
  • Check code No. P0270: No. 4 injector circuit low input (Refer to ).
  • Check code No. P0271: No. 4 injector circuit high input (Refer to ).

FUNCTION



  • The oxygen sensor (front) converts the concentration of oxygen in the exhaust emission into a voltage and inputs the signal to the engine-ECU.
  • When the air-fuel ratio is richer than the theoretical air-fuel ratio, the oxygen sensor (front) sends a voltage of about 1 V. When it is leaner than the theoretical air-fuel ratio, it sends a voltage of about 0 V.
  • In response to the signal, the engine-ECU controls the fuel injection amount so that the air-fuel ratio can be equivalent to the theoretical air-fuel ratio.

TROUBLE JUDGMENT


Check Conditions
  • Typically 20 seconds have passed since the engine starting sequence was completed.
  • Engine coolant temperature is more than 76°C. <4B11>
  • Engine coolant temperature is more than 60°C. <4B12>
  • Engine speed is more than 1,188 r/min.
  • Volumetric efficiency is more than 30 %.
  • Except while fuel is being shut off.
  • Monitoring time: 30 seconds.
Judgement Criterion
  • Oxygen sensor (front) output voltage does not get across lean/rich criteria (about 0.5 V) within about 30 seconds.

FAIL-SAFE AND BACKUP FUNCTION



  • None

PROBABLE CAUSES



  • Failed oxygen sensor (front)
  • Harness damage in oxygen sensor (front) circuit
  • Failed injector
  • Harness damage in injector circuit
  • Exhaust leak
  • Air drawn in from gaps in gasket, seal, etc.
  • Incorrect fuel pressure
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

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

  • Data list reference table (Refer to ).

  1. Item AC: Oxygen sensor (front)

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 for exhaust leaks.

Q. Is the check result normal?
Go to Step 3.
Repair.

STEP 3. Check for intake system vacuum leak.

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

STEP 4. Check oxygen sensor (front) itself.

  • Oxygen sensor (front) connector check.
  • Oxygen sensor (front) check (Refer to ).

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector, or replace the oxygen sensor (front).

STEP 5. Check injector itself.

  • No.1, No.2, No.3, No.4 injector connector check.
  • Injector check (Refer to ).

Q. Is the check result normal?
Go to Step 6.
Repair or replace the connector, or replace the injector.

STEP 6. Check harness between oxygen sensor (front) connector terminal and engine-ECU connector terminal O2FL.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 7.
Repair or replace the connector, or repair the damaged harness wire.

STEP 7. Check harness between injector connector and engine-ECU connector.

  1. Check and repair harness between No. 1 injector connector terminal and engine-ECU connector terminal INJ1.
  2. Check and repair harness between No. 2 injector connector terminal and engine-ECU connector terminal INJ2.
  3. Check and repair harness between No. 3 injector connector terminal and engine-ECU connector terminal INJ3.
  4. Check and repair harness between No. 4 injector connector terminal and engine-ECU connector terminal INJ4.

  • Check output line for damage.

Q. Are the check result normal?
Go to Step 8.
Repair or replace the connector, or repair the damaged harness wire.

STEP 8. Fuel pressure measurement.

  • Fuel pressure test (Refer to ).

Q. Is the check result normal?
Replace the engine-ECU.
Repair.