P0162 Malfunction in O2 Sensor Circuit B2S3

Code P0162: Definition and Meaning

The error code P0162 is a generic powertrain code related to the oxygen sensor (O2) circuit. It indicates a malfunction in the O2 sensor circuit for Bank 2 Sensor 3 (B2S3). This sensor, located downstream of the catalytic converter on cylinder bank 2, is crucial for monitoring the catalyst’s efficiency. Although generic, specific diagnostic procedures may vary between OBD-II equipped vehicle makes and models.

Role of the Post-Catalyst Oxygen Sensor

Oxygen sensors measure the O2 content in the exhaust gases. The Powertrain Control Module (PCM) uses this data to verify the catalytic converter’s efficiency. Unlike upstream sensors, the B2S3 sensor does not directly control the air-fuel mixture. It is a 4-wire sensor including a signal wire, a ground, a power supply, and a ground for its integrated heating element. This element allows the sensor to reach its operating temperature quickly, reducing emissions during cold starts.

Symptoms of Code P0162

A fault in the post-catalyst sensor often shows few visible symptoms to the driver. However, you might observe:

• Illumination of the Malfunction Indicator Lamp (MIL) on the dashboard.
• A slight decrease in fuel economy (km/L).
• An increase in polluting emissions, potentially leading to failure in emissions testing.
• In rare cases, the vehicle may enter a limp mode.

Possible Causes of Code P0162

Several issues can cause this fault code:

• Faulty O2 Sensor: Normal wear or fouling.
• Wiring Problem: Damaged wires rubbing against hot parts, short circuits, or corroded connectors.
• Failed Heater Circuit: Failure of the sensor’s internal heating element.
• Exhaust Problem: Leak or hole in the exhaust system near the sensor, skewing the readings.
• PCM Failure: Very rare, but possible.

Diagnosis and Solutions for Resolving P0162

Here is a step-by-step diagnostic procedure to identify and fix the cause of code P0162.

Step 1: Visual Inspection

Start with a thorough inspection under the vehicle:

• Check the condition of the Bank 2 Sensor 3 and its electrical connector for any visible damage or corrosion.
• Inspect the wiring harness along its entire length. Ensure it hasn’t melted on hot exhaust components and that all clips are secure.
• Look for any leaks or holes in the exhaust pipe near the sensor. Any outside air leak will distort the reading.

Step 2: Real-Time Data Analysis

Using an OBD-II scan tool, observe the live data from the B2S3 sensor:

1. Start the engine and let it reach its normal operating temperature.
2. Locate the B2S3 sensor’s signal voltage. A consistently low voltage (close to 0.1V) that does not vary is symptomatic.
3. Rev the engine to ~2000 RPM for one minute. Observe if the voltage finally starts to fluctuate between 0.1V and 0.9V. If it does after this period, the sensor’s heating element is likely faulty.

Step 3: Sensor and Wiring Test

If the voltage remains low and inactive:

1. With the engine off, disconnect the O2 sensor connector.
2. Turn the ignition on (without starting the engine). Your scan tool should now display a reference voltage of about 0.5V (half a volt) for this circuit.
3. If the reading changes to ~0.5V, this confirms that the PCM and wiring up to the connector are good. The sensor is faulty and needs replacement.
4. If the reading remains stuck low even after disconnecting the sensor, the problem lies with the wiring or the PCM. Use a multimeter to check for a short to ground on the signal wire. Also verify that the 0.5V reference voltage is present at the connector plug.

Conclusion and Call to Action

The code P0162 indicates a problem with the oxygen sensor circuit located after the catalyst on bank 2. Although often without immediate consequences for driving, it should not be ignored to ensure the proper functioning of your vehicle’s emissions control system and to pass emissions testing.

If the diagnostic steps seem complex, consult a professional mechanic. An accurate diagnosis using an advanced scan tool will prevent you from replacing parts unnecessarily. Use quality replacement parts to ensure the longevity of the repair.