Federal
Heated Oxygen Sensor (front) Circuit:
CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the PCM (terminal 71) from the output terminal (terminal 1) of the heated oxygen sensor (front).
- Terminal 2 of the heated oxygen sensor (front) is grounded with PCM (terminal 57).
TECHNICAL DESCRIPTION
- The heated oxygen sensor (front) detects the concentration of oxygen in the exhaust gas; it converts that data to voltage, and sends it to the PCM.
- When the heated oxygen sensor (front) begins to deteriorate, the heated oxygen sensor signal response deteriorates also.
- The PCM forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the heated oxygen sensor (front). In addition, the PCM also checks for an open circuit in the heated oxygen sensor (front) output line.
DTC SET CONDITIONS
Check Condition
- Heated oxygen sensor (front) signal voltage has continued to be 0.2 volt or lower for three minutes or more after engine start.
- Engine coolant temperature is higher than 82 °C (180 °F).
- Engine speed is higher than 1,200 r/min.
- Volumetric efficiency is higher than 25 percent.
- Monitoring time: 7 seconds.
Judgment Criteria
- Input voltage supplied to the PCM interface circuit is higher than 4.5 volts when 5 volts is applied to the heated oxygen sensor (front) output line.
- Only one monitor during one drive cycle
Check Condition
- Engine coolant temperature is higher than 50 °C (176 °F).
- Engine speed is at between 1,250 and 3,000 r/min.
- Volumetric efficiency is at between 20 and 60 percent.
- Intake air temperature is higher than -10 °C (14 °F).
- Barometric pressure is higher than 76 kPa (11 psi).
- Under the closed loop air/fuel control.
- Vehicle speed is 30 km/h (18.7 mph) or more
- Throttle valve opening angle (TPS output voltage) fluctuates within 0.117 volts every 250 milliseconds.
- Monitoring time: 5 - 20 seconds.
Judgment Criteria
- When the air/fuel ratio is forcibly changed (lean to rich), the heated oxygen sensor (front) signal does not provide response within 0.7 second.
or
- The heated oxygen sensor (front) sends "lean" and "rich" signals alternately eleven times or less for 12 seconds.
- Three monitors during one drive cycle
NOTE: If the sensor switch time is longer than the Judgment Criteria due to the MUT-II OBD-II test Mode - HO2S Test Results, it is assumed that the heated oxygen sensor has deteriorated. If it is short, it is assumed that the harness wire is broken or has a short circuit.
If the heated oxygen sensor signal voltage has not changed even once (lean/rich) after the DTC was erased, the sensor switch time will display as 0 seconds.
TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Heated oxygen sensor (front) deteriorated.
- Open circuit in heated oxygen sensor (front) output line.
- Open circuit in heated oxygen sensor (front) ground line.
- PCM failed.
DIAGNOSIS
Required Special Tools:
MB991502: Scan Tool (MUT-II)
MB991658: Test Harness Set
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
STEP 1. Using scan tool MB991502, check data list item 11: Heated Oxygen Sensor (front).
1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to the data reading mode for item 11, Heated Oxygen Sensor (front).
- Warm up the engine. When the engine is decelerated suddenly from 4,000 r/min, the output voltage should increase from 200 mV or less to 600 - 1,000 mV in a few seconds.
- Warm up the engine. When the engine speed is 2,000 r/min, more than 0.5 volt and less than 0.5 volt should alternate five times of more within 10 seconds.
If the checks above meet the specification, this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope With Intermittent Malfunction.
If the checks above do not meet the specification, go to Step 2.
STEP 2. Check the heated oxygen sensor (front).
1. Disconnect the heated oxygen sensor (front) connector C-18 and connect test harness special tool, MB991658, to the connector on the heated oxygen sensor (front) side.
2. Warm up the engine until engine coolant is 80 °C (176 °F) or higher.
CAUTION: Be very careful when connecting the jumper wires. Incorrect connection can damage the heated oxygen sensor (front).
3. Use the jumper wires to connect terminal 3 of the heated oxygen sensor (front) connector to the positive battery terminal and terminal 4 to the negative battery terminal.
4. Connect a digital voltmeter between terminal 1 and terminal 2.
5. While repeatedly revving the engine, measure the heated oxygen sensor (front) output voltage.
Standard value: 0.6 - 1.0 V
If within specifications, go to Step 3.
If not within specifications, replace the heated oxygen sensor (front).
Then go to Step 7.
STEP 3. Check harness connector C-18 at the heated oxygen sensor (front) for damage.
If harness connector C-18 is in good condition, go to Step 4.
If harness connector C-18 is damaged, repair or replace it.
Refer to Harness Connector Inspection.
Then go to Step 7.
STEP 4. Check harness connectors C40, C-41 at the PCM for damage.
If harness connector C-40, C-41 are in good condition, go to Step 5.
If harness connector C-40, C-41 are damaged, repair or replace it.
Refer to Harness Connector Inspection.
Then go to Step 7.
STEP 5. Check the harness wire between heated oxygen sensor (front) connector C-40, C-41
If the wires between heated oxygen sensor (front) connector C-18 and PCM connector C-40, C-41 are not damaged, go to Step 6.
If the wires between heated oxygen sensor (front) connector C-18 and PCM connectors C-40, C-41 are damaged, repair it. Then go to Step 7.
STEP 6. Replace the heated oxygen sensor (front).
1. Replace the heated oxygen sensor (front).
2. Carry out a test drive with the drive cycle pattern. Refer to Procedure 4 - Heated Oxygen Sensor Monitor and Procedure 6 - Other Monitor.
3. Check for the diagnostic trouble code (DTC).
If DTC P0130 is not output, the inspection is complete.
If DTC P0130 is output, replace the PCM. Then go to Step 7.
STEP 7. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 4 - Heated Oxygen Sensor Monitor and Procedure 6 - Other Monitor.
2. Read the diagnostic trouble code, and confirm that diagnostic trouble code P0130 dose not reset.