Troubleshooting

DTC P0150 Heated Oxygen Sensor Circuit (Bank 2 Sensor 1) (Except California)






CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used, but for the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The A/F sensor has the characteristic that provides output voltage* approximately proportional to the existing air-fuel ratio. The A/F sensor output voltage is used to provide feedback for the ECM to control the air-fuel ratio.
By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air-fuel ratio and control the proper injection time immediately. If the A/F sensor is malfunctioning, ECM is unable to perform accurate air-fuel ratio control.
The A/F sensor is equipped with a heater which heats the zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temp. of the exhaust gas is low), current flows to the heater to heat the sensor for accurate oxygen concentration detection.
*: The voltage value changes at the inside of the ECM only.





DETECTING CONDITIONS

HINT:
- Bank 1 refers to the bank that includes cylinder No.1.
- Bank 2 refers to the bank that does not include cylinder.
- No.1. Sensor 1 refers to the sensor closer to the engine body.
- The heated oxygen sensor's output voltage and the short-term fuel trim value can be read using the OBD II scan tool or LEXUS hand-held tester.





WIRING DIAGRAM





CONFIRMATION DRIVING PATTERN
a. Connect the LEXUS hand-held tester to the DLC3.
b. Switch the LEXUS hand-held tester from normal mode to check mode.
c. Start the engine and warm it up with all accessory switches OFF.
d. Drive the vehicle at 50 - 65 kph (31 - 40 mph) for 1 - 3 min. to warm up the heated oxygen sensor.
e. Let the engine idle for 1 mm.
f. Perform steps (c) to (e) three times.

HINT: If a malfunction exists, the MIL will light up during step (f).

NOTE: If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.
If you do not have a LEXUS hand-held tester, turn the ignition switch OFF after performing steps (c) to (f), then perform steps (c) to (f) again.

Step 1:

Step 2:

Step 3:

Step 4:

Step 5:

Step 6:

Step 7:

Step 8:

INSPECTION PROCEDURE

HINT: Read freeze frame data using LEXUS hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining whether the vehicle was running or stopped, the engine warmed up or not, the air-fuel ratio lean or rich, etc. at the time of the malfunction.