DTC P0156: O2 Sensor Circuit Malfunction (bank 2 sensor 2)

CIRCUIT OPERATION
• A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the PCM (terminal 73) from the output terminal (terminal 4) of the left bank heated oxygen sensor (rear).
• Terminal 2 of the left bank heated oxygen sensor (rear) is grounded with PCM (terminal 57).
TECHNICAL DESCRIPTION
• The output signal of the left bank heated oxygen sensor (front) is compensated by the output signal of the left bank heated oxygen sensor (rear).
• The PCM checks for an open circuit in the left bank heated oxygen sensor (rear) output line.
DTC SET CONDITIONS

Check Conditions
Left bank heated oxygen sensor (rear) signal voltage has continued to be 0.15 volt or lower for three minutes or more after the starting sequence was completed.
Engine coolant temperature is higher than 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 (rear) output line via a resistor.
• Only one monitor during one drive cycle.

Check Conditions
Left bank heated oxygen sensor (rear) signal voltage has continued to be 0.15 volt or lower for three minutes or more after the starting sequence was completed.
Engine coolant temperature is higher than 82°C (180°F).
Engine speed is higher than 1,200 r/min.
Volumetric efficiency is higher than 25 percent.
Volume air flow sensor output frequency is 100 Hz or more.
At least twenty seconds have passed since fuel shut off control was canceled.
The left bank heated oxygen sensor (front) outputs 0.5 volts or more.
Monitoring time: 10 seconds

Judgement Criteria
• Making the air/fuel ratio 15 percent for 10 seconds richer does not result in raising the left bank heated oxygen sensor (rear) output voltage beyond 0.15 volt.
• Only one monitor during one drive cycle.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
• Left bank heated oxygen sensor (rear) failed.
• Open circuit in left bank heated oxygen sensor (rear) output line.
• Open circuit in left bank heated oxygen sensor (rear) ground line.
• PCM failed.