Code P0163 indicates that the engine computer has detected an abnormally low voltage signal from the oxygen sensor located on Bank 2, Sensor 3. This sensor is typically positioned downstream of the catalytic converter, and a low voltage reading suggests the circuit is either reporting a false lean condition or experiencing an electrical short to ground.
The sensor itself has degraded internally or the sensing element has failed, causing it to output a constant low voltage or no voltage signal.
The signal wire is chafed, melted, or corroded, causing a short to ground, or the connector pins have lost proper contact.
An exhaust leak near the Bank 2 Sensor 3 location allows excess oxygen into the exhaust stream, tricking the sensor into reporting a genuinely lean condition.
A severe lean condition caused by vacuum leaks, low fuel pressure, or clogged injectors can cause low voltage readings, though this usually affects upstream sensors as well.
A rare internal fault within the engine computer prevents it from reading the sensor voltage correctly.
Generally, yes. Because Bank 2 Sensor 3 is a downstream sensor used primarily to monitor catalyst efficiency rather than control fuel trim, the vehicle will usually run normally. However, it will fail an emissions test and should be repaired promptly.
No. This code specifically indicates a low voltage problem with the sensor circuit itself. While a failing catalytic converter can alter sensor readings, P0163 points to a lean signal or electrical short rather than a degraded catalyst.
Almost never. Replacing the engine computer is an extremely unlikely fix for this code and is commonly an incorrect recommendation. The root cause is almost always a failed sensor, damaged wiring, or an exhaust leak.
It depends on the vehicle layout. Because it is a downstream sensor (located after the catalytic converter), it is often tucked up under the chassis and may require lifting the vehicle safely to access it properly.