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. P0264: No. 2 injector circuit low input (Refer to ).
Check code No. P0267: No. 3 injector circuit low input (Refer to ).
Check code No. P0270: No. 4 injector circuit low input (Refer to ).

FUNCTION

The engine-ECU effects air/fuel ratio feedback control in accordance with the signals from the oxygen sensor (front).
If the oxygen sensor (front) has deteriorated, corrections will be made by the oxygen sensor (rear).
Code No. P0134 becomes stored in memory if a failure is detected in the above air/fuel ratio feedback control system.

TROUBLE JUDGEMENT

Check Conditions

The engine starting sequence was completed.
Engine coolant temperature is more than 76°C.
Engine speed is more than 1,200 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 ).

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 check (Refer to ).

Q. Is the check result normal?

	Go to Step 5.

	Replace the oxygen sensor (front).

STEP 5. Check injector itself.

Injector check (Refer to ).

Q. Is the check result normal?

	Go to Step 6.

	Replace the injector.

STEP 6. Check of damage in O2FL line between oxygen sensor (front) connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 7.

	Repair the connector(s) or wiring harness.

STEP 7. Check of damage in INJ1, INJ2, INJ3 line between injector connector and engine-ECU connector.

Check and repair harness between No. 1 injector connector and engine-ECU connector (terminal code INJ1).
Check and repair harness between No. 2 injector connector and engine-ECU connector (terminal code INJ2).
Check and repair harness between No. 3 injector connector and engine-ECU connector (terminal code INJ3).

Check output line for damage.

Q. Are the check result normal?

	Go to Step 8.

	Repair the connector(s) or wiring harness.

STEP 8. Fuel pressure measurement.

Fuel pressure test (Refer to ).

Q. Is the check result normal?

	Replace the engine-ECU.

	Repair.