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P0150

Left Bank Heated Oxygen Sensor (front) Circuit:




Connector: C-71:




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 4) of the left bank heated oxygen sensor (front).
- Terminal 2 of the left bank heated oxygen sensor (front) is grounded with PCM (terminal 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 PCM.
- When the left bank heated oxygen sensor (front) begins to deteriorate, the heated oxygen sensor signal response deteriorates also.
- The 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 PCM also checks for an open circuit in the left bank heated oxygen sensor (front) output line.

DTC SET CONDITIONS

Check Area
- Left bank 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 approximately 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 left bank heated oxygen sensor (front) output line.
- Only one monitor during one drive cycle.

Check Area
- 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 25 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 left bank heated oxygen sensor (front) signal does not provide response within 1.1 seconds.
or
- The left bank heated oxygen sensor (front) sends "lean" and "rich" signals alternately eleven times or less for 12 seconds.
- Monitored three times 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:
- 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.
- PCM failed.

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

CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.




STEP 1. Using scan tool MB991502, check data list item 39: Heated Oxygen Sensor (front).
- The output voltage should be 0.6 and 1.0 volt when sudden racing is carried out after the engine has been warmed.

- When the engine speed is 2,000 r/min, more than 0.5 volt and less than 0.5 volt alternate five times or more within 10 seconds.

If the checks above do not meet the specification, go to Step 2.

If the checks above meet the specification, it can be assumed that this malfunction is intermittent. Refer to vehicle level Testing and Inspection.

STEP 2. Check the left bank heated oxygen sensor (front).
Refer to Heated Oxygen Sensor Check.

If correct, go to Step 3.

If incorrect, replace the left bank heated oxygen sensor (front).

Then go to Step 6.







STEP 3. Check the harness wire between the left bank heated oxygen sensor (front) connector A-09 and the PCM connectors C-90, C-91.

NOTE: After inspecting the intermediate connector C-71, inspect the wire. If the intermediate connector C-71 is damaged, repair or replace it. Refer to vehicle level Testing and Inspection. Then go to Step 6

If the wire between the left bank heated oxygen sensor (front) connector A-09 and the PCM connectors C-90, C-91 are not damaged, go to Step 4.

If the wire between the left bank heated oxygen sensor (front) connector A-09 and the PCM connectors C-90, C-91 are damaged, repair it. Then go to Step 6.







STEP 4. Check for damage of the harness connector A-09 at the left bank heated oxygen sensor (front) and the harness connectors C-90, C-91 at the PCM.

If harness connectors A-09, and C-90, C-91 are in good condition, go to Step 5.

If harness connectors A-09, and C-90, C-91 are damaged, repair or replace them. Refer to vehicle level Testing and Inspection. Then go to Step 6.

STEP 5. Replace the left bank heated oxygen sensor (front).
1. Replace the left bank 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 P0150 is output, replace the PCM. Then go to Step 6.

If DTC P0150 is not output, the inspection is complete.

STEP 6. 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 a diagnostic trouble code is not being output.







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