DTC P0138: Heated Oxygen Sensor Circuit High Voltage (bank 1 sensor 2)

CIRCUIT OPERATION
• A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the PCM (terminal No. 74) from the output terminal (terminal No. 4) of the right bank heated oxygen sensor (rear).
• Terminal No. 2 of the right bank heated oxygen sensor (rear) is grounded with PCM (terminal No. 57).
TECHNICAL DESCRIPTION
• The output signal of the right bank heated oxygen sensor (front) is compensated by the output signal of the right bank heated oxygen sensor (rear).
• The PCM checks for an open circuit in the right bank heated oxygen sensor (rear) output line.
DESCRIPTIONS OF MONITOR METHODS
Right bank heated oxygen sensor (rear) output voltage is over specified range.
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
2 minutes or more have passed since the starting sequence was completed.

Judgment Criteria
• Right bank heated oxygen sensor (rear) output voltage has continued to be 1.2 volts or higher for 2 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:
• Short circuit in right bank heated oxygen sensor (rear) output line.
• Connector damage.
• PCM failed.