Technical Description of OBD-II Trouble Code
Malfunction in the O2 Sensor Circuit (Bank 2 Sensor 3)
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to vehicles equipped with OBD-II. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The O2 (oxygen) sensors measure the oxygen content in the exhaust, whether it is rich or lean. The PCM (powertrain control module) uses this information to regulate the fuel injector pulse in order to maintain the proper air:fuel ratio. The O2 sensors play a crucial role in the engine’s proper operation.
Fouled or faulty O2 sensors can cause the PCM to add or remove fuel based on inaccurate O2 sensor data, leading to a false lean or rich condition. The P0162 code refers to the Bank 2,3 O2 sensor, which is the third sensor downstream (post-cat) on Bank 2. It is a four-wire sensor. The PCM provides a ground circuit and a reference voltage circuit of approximately 0.5 volts. Additionally, there is a battery voltage supply wire for the O2 sensor heater element (usually from the power distribution center) and another ground circuit for it. The O2 sensor heater allows the sensor to warm up faster, enabling closed loop operation in less time than it would normally take for the exhaust to warm the sensor to operating temperature. This reduces exhaust emissions during cold startup. The O2 sensor varies the supplied reference voltage based on the oxygen content in the exhaust, ranging from about 0.1 to 0.9 volts. A voltage of 0.1 V indicates lean exhaust, while 0.9 V indicates rich exhaust. The P0162 code indicates that the Bank 2, 3 O2 sensor is stuck low for an extended period or is inactive.
Symptoms
Post-cat O2 sensor problems often do not cause significant drivability issues since they are used by the PCM to monitor the quality of the catalytic converter and do not directly control fuel. In some cases, no noticeable symptoms are present. However, the following symptoms may occur in certain vehicles:
Causes
Possible causes of a P0162 code include:
Possible Solutions
Warm the engine up to normal operating temperature. Using your scan tool’s live datastream, check the signal voltage for the Bank 2,3 O2 sensor at idle. Is it stuck low and not switching? If so, increase the engine RPMs for a minute or so and observe if the sensor starts switching or changing voltage. If it does after a period of elevated idle, inspect the exhaust components underneath the vehicle for rust or holes near the O2 sensor(s). Repair as necessary. If the exhaust is intact, suspect a sluggish Bank 2,3 O2 sensor and replace it. If the O2 sensor continues to show a low reading on the datastream, unplug it and observe the reading. It should now display the reference voltage, or half a volt (0.5 V). If it does, check for connector issues, water intrusion, sensor damage, etc. If everything is fine, replace the faulty Bank 2,3 O2 sensor.
If the voltage reading remains low after unplugging the O2 sensor, suspect a wiring problem. Visually inspect the wiring harness, ensuring that it does not come into contact with hot exhaust components and that all harness retainers are in place. Repair as necessary. If there are no wiring harness issues, use a voltmeter to check for reference voltage from the PCM at the unplugged connector. It should read the reference voltage, or approximately half a volt (0.5 V). If the voltage reading is too high, repair the short to voltage on the signal circuit.
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