Code No. P0130: Oxygen Sensor (Front) System

OPERATION

The sensor signal is inputted to the engine-ECU (terminal No. 97) from the oxygen sensor (front) output terminal (terminal No. 1).
The oxygen sensor (front) (terminal No. 2) is earthed with engine-ECU (terminal No. 98).

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) outputs a voltage of about 1 V. When it is leaner than the theoretical air-fuel ratio, it outputs 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

Above 3 minutes later after the engine has started up.
The engine coolant temperature is approximately 82°C or higher.
The engine speed is 1,200 r/min or more.
The monitoring time is 10 seconds.

Judgment Criteria

When the oxygen sensor (front) output voltage is 0.2 V or less and a power voltage of 5 V is applied to the oxygen sensor (front) in the engine-ECU, the sensor output voltage is 4.5 V or more.
To be monitored once per driving cycle.

Check Conditions

The engine speed is 1,200 - 3,000 r/min.
The engine coolant temperature is approximately 60°C or higher.
Volumetric efficiency is 20 - 60%.
During the air-fuel ratio feedback control

Judgment Criterion

When the oxygen sensor (front) output frequency is 9 or less for 10 seconds on the average.

PROBABLE CAUSES

Failed oxygen sensor (front)
Open/short circuit and damage in oxygen sensor (front) circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Refer to Data List Reference Table .

Item No. 9: 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. Connector check: A-145 oxygen sensor (front) connector

Q. Is the check result normal?

Go to Step 3 .

Repair or replace the connector.

STEP 3. Perform resistance measurement at A-145 oxygen sensor (front) connector.

Disconnect connector, and measure at harness side.
Resistance between terminal No. 2 and earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

Go to Step 7 .

Go to Step 4 .

STEP 4. Connector check: A-35 engine-ECU connector

Q. Is the check result normal?

Go to Step 5 .

Repair or replace the connector.

STEP 5. Check harness between A-145 (terminal No. 2) oxygen sensor (front) connector and A-35 (terminal No. 98) engine-ECU connector.

note

Before checking harness, check intermediate connector A-36, and repair if necessary.

Check earthing line for open circuit and damage.

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 .

Item No. 9: 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 ).

	Replace the engine-ECU then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding ).

STEP 7. Perform voltage measurement at A-145 oxygen sensor (front) connector.

Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
Engine: After warm-up
Transmission: Neutral
Voltage between terminal No.1 and earth.

OK:
When the engine is 2,500 r/min, the output voltage should repeat 0 to 0.8 V alternately.

Q. Is the check result normal?

Go to Step 10 .

Go to Step 8 .

STEP 8. Check oxygen sensor (front) itself.

Check oxygen sensor (front) itself (Refer to ).

Q. Is the check result normal?

	Go to Step 9 .

	Replace the oxygen sensor (front).

STEP 9. Connector check: A-35 engine-ECU connector

Q. Is the check result normal?

Check output line for short circuit.

Repair or replace the connector.

STEP 10. Perform voltage measurement at A-35 engine-ECU connector.

Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB991987), and then measure the voltage on the check connector.
Transmission: Neutral
Engine: After warm-up
Voltage between terminal No. 97 and earth.

OK:
When the engine is 2,500 r/min, the output voltage should repeat 0 to 0.8 V alternately.

Q. Is the check result normal?

Go to Step 12 .

Go to Step 11 .

STEP 11. Connector check: A-35 engine-ECU connector

Q. Is the check result normal?

Check output line for open circuit and damage.

Repair or replace the connector.

STEP 12. Connector check: A-35 engine-ECU connector

Q. Is the check result normal?

Repair or replace the connector.