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P0162 — O2 Sensor Circuit Bank 2 Sensor 3

Generic OBD-II · all makesPowertrain (engine & transmission)

P0162 indicates a problem with the oxygen sensor circuit for Bank 2, Sensor 3 (the downstream O2 sensor after the catalyst). The ECM has detected a voltage signal that is out of the expected range, suggesting a fault in the sensor, wiring, or related components.

Symptoms

What causes it — most likely first

1. Faulty Bank 2 Sensor 3 (downstream O2 sensor)

The sensor element can fail electrically or become contaminated, causing erratic voltage readings.

2. Wiring harness damage or poor connections

Corroded pins, broken wires, or loose connectors can interrupt the sensor signal.

3. Exhaust leak upstream of the sensor

A leak before the sensor can introduce extra oxygen, confusing the sensor and producing out‑of‑range voltages.

4. Failed sensor heater circuit

If the sensor's heater element does not reach operating temperature, the sensor may output invalid voltages.

5. ECM/PCM internal fault (rare)

Only after eliminating sensor, wiring, and exhaust issues should the control module be considered, as it is rarely the root cause.

How it's diagnosed

  1. Visually inspect the Bank 2 Sensor 3 wiring and connector for corrosion, damage, or loose pins.
  2. Measure sensor voltage with a multimeter while the engine is at operating temperature; compare to specifications (typically 0.1‑0.9 V fluctuating).
  3. Test the sensor heater resistance to ensure it is within the manufacturer's range.
  4. Check for exhaust leaks upstream of the sensor using a smoke test or visual inspection.
  5. If all hardware tests are normal, perform an ECM reflash or swap with a known‑good unit to verify the module is not at fault.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0160 — O2 Sensor Circuit No Activity DetectedP0161 — O2 Sensor Heater Circuit Bank 2 SensorP0163 — O2 Sensor Circuit Low Voltage Bank 2 SP0164 — O2 Sensor Circuit High Voltage Bank 2 P0165 — O2 Sensor Circuit Slow Response Bank 2P0166 — O2 Sensor Circuit No Activity Detected

Frequently asked

Do I need to replace the PCM for a P0162 code?

Almost never. The PCM is a very unlikely cause; replace it only after confirming the sensor, wiring, and exhaust are all functioning correctly.

Can a bad O2 sensor cause my car to fail an emissions test?

Yes. A malfunctioning downstream sensor can cause the engine to run richer or leaner than optimal, leading to higher emissions.

Is it normal for the downstream O2 sensor to show a steady voltage?

The downstream sensor is primarily used to monitor catalyst efficiency and typically shows a relatively stable voltage. However, it should still vary slightly with engine load; a completely steady voltage may indicate a fault.

Will cleaning the sensor fix the P0162 code?

Cleaning may help if the sensor is merely contaminated, but most O2 sensors are not serviceable. Replacement is often the most reliable solution if the sensor fails diagnostic tests.