P0163 OBD-II trouble code: 02 Sensor Circuit Low Voltage (Bank 2, Sensor 3)

Check Engine Light

P0163 code definition

Trouble code P0163 is set when low voltage is detected on the bank 2 sensor 2 oxygen sensor circuit.

What the P0163 code means

Bank 2 refers to the side of the engine opposite of cylinder number 1. Sensor 3 means that it is the third sensor in the exhaust, which is usually after the catalytic converter to monitor its efficiency.

This code means that the powertrain control module has detected a low voltage condition in the circuit for the oxygen sensor for bank 2 sensor 3. The Check Engine Light will illuminate to let the owner know that there is a problem with the emissions system.

What causes the P0163 code?

Trouble code P0163 sets when the engine management computer detects low voltage on the oxygen sensor circuit for bank 2 sensor 3.

Generally, an oxygen sensor’s voltage will vary up and down. The first sensor in the exhaust varies voltage very quickly and the voltage variance is greater. The second and third sensors vary slower, and the voltage variance is smaller due to the catalyst in the exhaust.

When the computer detects that there is no activity or variance in the voltage it sees this as a problem and sets this error code. Low voltage in an oxygen sensor could be an indication of a lean condition in the exhaust. Lean means that there is too much oxygen. This low voltage could also be due to a fault in the circuit.

What are the symptoms of the P0163 code?

The main symptom for this code is that the Check Engine Light will come on. There are no drivability problems typically associated when this code sets.

How does a mechanic diagnose the P0163 code?

  • As with any oxygen sensor code, I recommend performing a visual check of the oxygen sensor harness to look for any obvious signs of damage. They are under the vehicle and are susceptible to damage by road hazards.

  • For this particular code, it is a good idea to check for any exhaust leaks. Leaks in the exhaust could let in outside air and skew the sensors reading to make the mixture in the exhaust lean. If there is a lean condition due to an exhaust leak, P0163 could set.

  • Next, check the terminals of the connector for any signs of corrosion or water intrusion. These will cause the voltage readings to be incorrect causing an error code.

  • Next, check the resistance of the oxygen sensor itself and make sure it is within specifications.

  • After the oxygen sensor resistance checks out okay, you need to measure the reference voltage from the powertrain control module. If all of these checks turn out okay, it is most likely a faulty oxygen sensor.

  • A quick way to check for this is to monitor the voltage of the sensor with a scan tool and either introduce a vacuum leak or an extra fuel source to the vehicle. This should change the voltage reading to one extreme or the other for the sensor. If there is no change this confirms that the sensor is not reading correctly.

Common mistakes when diagnosing the P0163 code

The most common mistake would be replacing the oxygen sensor without performing any diagnostics and then still having the problem.

The next common problem would be be replacing the wrong sensor. Depending on the engine configuration, it is possible to get the cylinder banks confused if you do not consult the service information for the vehicle you are working on.

Another problem is not identifying an exhaust leak that is causing the oxygen sensor to indicate low voltage due to a lean mixture in the exhaust.

How serious is the P0163 code?

There will be no drivability concerns related to this trouble code. However, this trouble code will cause you to fail an emissions test if their test equipment connects to the engine computer to check for codes. If they run your car on a dyno there is a possibility that your car may pass the test as long as there are no other issues.

What repairs can fix the P0163 code?

The most common repair is replacing the faulty oxygen sensor. After a faulty oxygen sensor, I would say correcting a lean condition in the exhaust due to a leak would be next. Finally, after that, I would say that wiring repairs are the next most common repair for this trouble code.

Need help with a P0163 code?

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The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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