P0131
DTC P0131: Heated Oxygen Sensor Circuit Low Voltage (sensor 1)Heated Oxygen Sensor (front) Circuit Part 1:
Heated Oxygen Sensor (front) Circuit Part 2:
CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal 76)
- Terminal 2 of the heated oxygen sensor (front) is grounded with ECM (terminal 92)
TECHNICAL DESCRIPTION
- The heated oxygen sensor (front) detects the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the ECM
- When the heated oxygen sensor (front) begins to deteriorate, the heated oxygen sensor signal response becomes poor.
- The ECM
DTC SET CONDITIONS
Check Conditions
- 3 minutes or more have passed since the starting sequence was completed.
- Heated oxygen sensor (front) signal voltage has continued to be 0.2 volt or lower.
- Engine coolant temperature is higher than 76 °C (169 °F).
- Engine speed is higher than 1,200 r/min.
- Volumetric efficiency is higher than 25 percent.
- Volume air flow sensor output frequency is 75 Hz or more.
- At least 20 seconds have passed since fuel shut off control was canceled.
- After the ignition switch is turned ON, the changes in the output voltage of the heated oxygen sensor (front) is lower than 0.078 volt.
- Monitoring time: 10 seconds.
Judgement Criteria
- Making the air/fuel ratio 15 percent for 10 seconds richer does not result in raising the heated oxygen sensor (front) output voltage beyond 0.2 volt.
- The ECM
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Heated oxygen sensor (front) deteriorated.
- Short circuit in heated oxygen sensor (front) output line.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991502: Scan Tool (MUT-II)
- MD998464: Test Harness
STEP 1. Using scan tool MB991502, check data list item 11: Heated Oxygen Sensor (front).
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
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).
- Warming up the engine. When the engine is revved, the output voltage should be 0.6 to 1.0 volt.
- Warming up the engine. When the engine is idling, the output voltage should repeat 0.4 volt and 0.6 to 1.0 volt alternately.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.
NO: Go to Step 2.
STEP 2. Check the heated oxygen sensor (front).
1. Disconnect the heated oxygen sensor (front) connector B-17 and connect test harness special tool, MD998464, to the connector on the heated oxygen sensor (front) side.
2. Warm up the engine until engine coolant 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 1 (red clip) to the positive battery terminal and terminal 3 (blue clip) to the negative battery terminal.
4. Connect a digital volt meter between terminal 2 (black clip) and terminal 4 (white clip).
5. While repeatedly revving the engine, measure the heated oxygen sensor (front) output voltage.
Standard value: 0.6 - 1.0 volt
Q: Is the voltage at the standard value?
YES: Go to Step 3.
NO: Replace the heated oxygen sensor (front). Then go to Step 5.
STEP 3. Check connector B-17 at heated oxygen sensor (front) and connector C-60 at ECM
Q: Is the connector in good condition?
YES: Go to Step 4.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 5.
STEP 4. Check for short circuit to ground between heated oxygen sensor (front) connector B-17 (terminal 4) and ECM connector C-60 (terminal 76)
Q: Is the harness wire in good condition?
YES: Replace the ECM or PCM. Then go to Step 5.
NO: Repair it. Then go to Step 5.
STEP 5. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 6 - Other Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is the DTC P0131 is output?
YES: Retry the troubleshooting.
NO: The inspection is complete.