P0153

Left Bank Heated Oxygen Sensor (front) Circuit:

Connectors:

CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No.71) or PCM (terminal No.71) from the output terminal (terminal No.4) of the left bank heated oxygen sensor (front).
- Terminal No.2 of the left bank heated oxygen sensor (front) is grounded with ECM (terminal No.49) or PGM (terminal No.57) .

TECHNICAL DESCRIPTION
- The left bank heated oxygen sensor (front) detects the concentration of oxygen in the exhaust gas; it converts that data to voltage, and sends it to the ECM or PCM .
- When the left bank heated oxygen sensor (front) begins to deteriorate, the heated oxygen sensor signal response deteriorates also.
- The ECM or PCM varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the left bank heated oxygen sensor (front). In addition, the ECM or PCM also checks for an open circuit in the left bank heated oxygen sensor (front) output line.

DTC SET CONDITIONS

Check Conditions
- Engine coolant temperature is higher than 50 °C (122 °F).
- Engine speed is at between 1,250 and 3,000 rpm.
- Volumetric efficiency is at between 20 and 60 percent.
- Under the closed loop air/fuel control.
- The throttle valve is open.
- Short-term fuel trim is higher than 30 percent and lower than +25 percent.
- More than 3 seconds have elapsed after the above mentioned conditions have been met.
- The ECM or PCM monitors for this condition for 7 cycles of 12 seconds each during the drive cycle.

Judgment Criteria
- The left bank heated oxygen sensor (front) sends "lean" and "rich" signals alternately 11 times or less for 12 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 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:)
- Left bank heated oxygen sensor (front) deteriorated.
- Open circuit in left bank heated oxygen sensor (front) output line.
- Open circuit in left bank heated oxygen sensor (front) ground line.
- ECM failed.
- PCM failed.

DIAGNOSIS

Required Special Tool:
- MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, check data list item 11: Heated Oxygen Sensor Bank 2, Sensor 1 (left 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 MB99i5O2.

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 Bank 2, Sensor 1 (left 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: Replace the left bank heated oxygen sensor (front). Then go to Step 2.

STEP 2. Test the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to Trouble Code Diagnosis - OBD-II Drive Cycle - Procedure 6 - Other Monitor.
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0153 set?

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