Code No. P0135: Cylinder 1, 4 Oxygen Sensor Heater System

OPERATION

Power is supplied to the heater power terminal (terminal No. 1) of the Cylinder 1, 4 oxygen sensor connector from the engine control relay (terminal No. 1).
The heater (terminal No. 3) of the Cylinder 1, 4 oxygen sensor connector is controlled by the power transistor in the engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 25).

FUNCTION

The power supply to the cylinder 1, 4 oxygen sensor heater is controlled by the ON/OFF control of the power transistor in the engine-ECU <M/T> or engine-A/T-ECU <A/T>.
Heating the cylinder 1, 4 oxygen sensor heater enables the cylinder 1, 4 oxygen sensor to provide good response even when the exhaust emission temperature is low.

TROUBLE JUDGMENT

Check Conditions

Engine coolant temperature is 20°C or higher.
While cylinder 1, 4 oxygen sensor (front) heater is on.
Engine speed is approximately 50 r/min or more.
Battery positive voltage is 11 - 16 V.

Judgment Criterion

Cylinder 1, 4 oxygen sensor (front) heater current has continued to be 0.2 A or less, or 7.5 A or more for 4.3 seconds.

PROBABLE CAUSE

Failed cylinder 1, 4 oxygen sensor heater
Open/short circuit in cylinder 1, 4 oxygen sensor circuit heater or loose connector contact
Failed engine-ECU <M/T>
Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-26 cylinder 1, 4 oxygen sensor connector

Q. Is the check result normal?

Go to Step 2 .

Repair or replace.

STEP 2. Perform resistance measurement at B-26 cylinder 1, 4 oxygen sensor connector.

Disconnect connector, and measure at sensor side.
Resistance between terminal No. 1 and No. 3.

OK: 11 - 18 Ω

Q. Is the check result normal?

Go to Step 3 .

Replace cylinder 1, 4 oxygen sensor.

STEP 3. Perform voltage measurement at B-26 cylinder 1, 4 oxygen sensor connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 1 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 5 .

Go to Step 4 .

STEP 4. Connector check: B-15X engine control relay connector

Q. Is the check result normal?

Check power supply line for open/short circuit.

Repair or replace.

STEP 5. Perform voltage measurement at C-110 engine-ECU <M/T> connector or engine-A/T-ECU <A/T> connector.

Measure engine-ECU <M/T> or engine-A/T-ECU <A/T> terminal voltage.
Ignition switch: ON
Voltage between terminal No. 25 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 8 .

Go to Step 6 .

STEP 6. Connector check: C-110 engine-ECU <M/T> connector or engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

Go to Step 7 .

Repair or replace.

STEP 7. Check harness between B-26 (terminal No. 3) cylinder 1, 4 oxygen sensor connector and C-110 (terminal No. 25) engine-ECU <M/T> connector or engine-A/T-ECU <A/T> connector.

Check earthing line for open/short circuit.

Q. Is the check result normal?

Replace engine-ECU <M/T> or engine-A/T-ECU <A/T>.

Repair.

STEP 8. Connector check: C-110 engine-ECU <M/T> connector or engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

Go to Step 9 .

Repair or replace.

STEP 9. Check harness between B-26 (terminal No. 1)cylinder 1, 4 oxygen sensor connector and B-15X (terminal No. 1) engine control relay connector.

note

Before checking harness check intermediate connector C-116, and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 10 .

Repair.

STEP 10. Check harness between B-26 (terminal No. 3) cylinder 1, 4 oxygen sensor connector and C-110 (terminal No. 25) engine-ECU <M/T> connector or engine-A/T-ECU <A/T> connector.

Check earthing line for damage.

Q. Is the check result normal?

Go to Step 11 .

Repair.

STEP 11. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Q. Is the diagnosis code set?

	Replace engine-ECU <M/T> or engine-A/T-ECU <A/T>.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).