P0133

Heated Oxygen Sensor(Front) Circuit:

Connectors:

DTC P0133: Heated Oxygen Sensor Circuit Slow Response (Sensor 1)

CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No.76) or PCM (terminal No.71) from the output terminal (terminal No.4) of the heated oxygen sensor (front).
- Terminal No.2 of the heated oxygen sensor (front) is grounded with ECM (terminal No. 92) or PCM (terminal No.57) .

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 or PCM .
- When the heated oxygen sensor (front) begins to deteriorate,the heated oxygen sensor signal response becomes poor.
- The ECM or 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 ECM or PCM also checks for an open circuit in the heated oxygen sensor (front)output line.

DESCRIPTIONS OF MONITOR METHODS
Heated oxygen sensor(front) rich/lean switching frequency is under specified value.

MONITOR EXECUTION
Continuous

MONITOR EXECUTION CONDITIONS
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Heated oxygen sensor heater (front) monitor
- Misfire monitor
- Fuel system monitor
Sensor (The sensor below is determined to be normal)
- Volume airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor
- Barometric pressure sensor
- Throttle position sensor

Logic Flow Chart:

DTC SET CONDITIONS

Check Conditions
- Engine coolant temperature is higher than 60 °C (140 °F).
- Engine speed is at between 1,500 and 3,000 or 1,200 and 3,000 rpm.
- Volumetric efficiency is at between 21 and 60 or 30 and 60 percent.
- Under the closed loop air/fuel control.
- The throttle valve is open.
- Short-term fuel trim is higher than -25 percent and lower than +25 percent.
- More than 2 seconds have elapsed after the above mentioned conditions have been met.
- The ECM or PCM monitors for this condition for 7 cycles of 10 seconds each during the drive cycle.

Judgment Criteria
- The heated oxygen sensor (front) sends "lean" and "rich" signals alternately 8 times or less for 10 seconds.

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 is damaged or has a shod 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.

OBD-LL Drive Cycle Pattern
Refer to Diagnostic Function - OBD-II drive Cycle-Procedure 4 - Heated Oxygen Sensor Monitor

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Heated oxygen sensor (front) deteriorated.

DIAGNOSIS

Required Special Tool:
- 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).
4. Warm-up the engine, 2500 rpm.
- Output voltage repeats 0.4 volt or less and 0.6 - 1.0 volt 10 times or more within 10 seconds.
5. 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:Then 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 temperature reaches 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 No.1 (red clip) to the positive battery terminal and terminal No.3 (blue clip) to the negative battery terminal.
4. Connect a digital volt meter between terminal No.2 (black clip) and terminal No. 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 between 0.6 and 1.0 volt?

YES: Go to Step 3.
NO: Replace the heated oxygen sensor (front).Then go to Step 4.

STEP 3. Check harness connector B-17 at heated oxygen sensor (front) and harness connector C-120 at ECM or C-114, C-117 at PCM for damage.

Q: Is the harness connector in good condition?

YES: Replace the ECM or PCM. Then go to Step 4.
NO: Repair or replace it. Refer to Harness Connector Inspection.Then go to Step 4.

STEP 4. Test the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function OBD-II Drive Cycle - Procedure 4 - Heated Oxygen Sensor Monitor.
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0133 set?

YES: Retry the troubleshooting.
NO: The inspection is complete.