DTC P0159: Heated Oxygen Sensor Circuit Slow Response (bank 2, sensor 2)

CIRCUIT OPERATION
• A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the PCM (terminal No. 73) from the output terminal (terminal No. 4) of the left bank heated oxygen sensor (rear).
• Terminal No. 2 of the left bank heated oxygen sensor (rear) is grounded with PCM (terminal No. 57).
TECHNICAL DESCRIPTION
• The output signal of the heated left bank 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.
DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (rear) output voltage does not change during specified go/stop operations including fuel cut are repeated.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
• Heated oxygen sensor heater (front) monitor
• Heated oxygen sensor heater (rear) monitor
• Air/fuel ratio feedback monitor

Sensor (The sensor below is determined to be normal)
• Volume airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor
DTC SET CONDITIONS Logic Flow Chart


Check Conditions
• Engine coolant temperature is higher than 76°C (169°F).
• The left bank heated oxygen sensor (front) is active.
• The cumulative volume airflow sensor output frequency is higher than 4,000 Hz.
• Repeat 3 or more times: drive*1, stop*2.
Drive*1:
• Engine speed is higher than 1,500 r/min.
• Volumetric efficiency is higher than 40 percent.
• Vehicle speed is higher than 30 km/h (18.7 mph).
• A total of more than 10 seconds have elapsed with the above mentioned conditions, and more than 2 seconds have elapsed with the fuel shut off.
Stop*2:
• Vehicle speed is lower than 1.5 km/h (0.9 mph).

Judgement Criteria
• Change in the output voltage of the left bank heated oxygen sensor (rear) is lower than 0.313 volt.
NOTE: Monitoring stops after fuel has been shut off for more than 38 seconds.
OBD-II 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:
• Left bank heated oxygen sensor (rear) failed.
• Connector damage.
• PCM failed.