P0160Powertrain
Powertrain · SAE
O2 Sensor Circuit No Activity — Bank 2, Sensor 2
Meaning
The downstream oxygen sensor on Bank 2 shows no voltage variation — the signal is fixed or absent. This indicates a dead sensor, an open circuit, or a heater failure that is keeping the sensor below its operating temperature.
Common causes
- Completely failed O2 sensor (Bank 2, Sensor 2) with non-functional ceramic element
- Open heater circuit preventing the sensor from reaching operating temperature
- Open signal circuit due to broken wiring or disconnected connector
- Signal shorted to a fixed potential, preventing any voltage variation
- Missing sensor supply voltage due to a blown fuse or failed relay
- Internal ECU fault in the signal acquisition circuit
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- O2 sensor data appears fixed or absent in the scan tool data stream
- Catalyst efficiency monitoring completely compromised
- No noticeable driveability symptoms in most cases
Severity
Moderata: The vehicle is generally driveable, but the emissions monitoring system is completely blind on Bank 2; if the root cause is a heater failure, the sensor never reaches operating temperature and cannot fulfil any diagnostic role.
What to do
- Use a scan tool to confirm the sensor signal is genuinely fixed or absent both cold and at operating temperature
- Check supply voltage and ground at the heater circuit; measure the resistance of the heating element
- Inspect the signal wiring for open circuits, shorts, or disconnected connectors
- Verify that supply voltage is present at the sensor connector with the ignition on
- Replace the O2 sensor if the external circuit is intact; if the fault persists after replacement, diagnose the ECU-side circuit