DTC P0139: O2 Sensor Circuit Slow Response (bank 1 sensor 2)

CIRCUIT OPERATION
• A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the PCM (terminal 74) from the output terminal (terminal 4) of the right bank heated oxygen sensor (rear).
• Terminal 2 of the right bank heated oxygen sensor (rear) is grounded with PCM (terminal 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.
DTC SET CONDITIONS

Check Conditions
• Engine coolant temperature is higher than 82°C (180°F).
• Barometric pressure is higher than 76 kPa (11 psi).
• The right bank heated oxygen sensor (front) is active.

Judgement Criteria
• The right bank heated oxygen sensor (rear) output voltage, before the fuel shut off is started, was 0.4 volts or more, and during the shut off, it takes one second or more for the right bank heated oxygen sensor (rear) output voltage to fall from 0.4 to 0.15 volts.
or
• The right bank heated oxygen sensor (rear) output voltage, before the fuel shut off is started, was 0.15 volts or more, and during the shut off, it takes three seconds or more for the right bank heated oxygen sensor (rear) output voltage to fall below 0.15 volts.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
• Right bank heated oxygen sensor (rear) failed.
• Open circuit in right bank heated oxygen sensor (rear) output line.
• Open circuit in right bank heated oxygen sensor (rear) ground line.
• PCM failed.