P0163 — O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)
Drive with caution — fix soon.
What P0163 means
This code means the engine computer detected a general electrical malfunction in the bank 2 sensor 3 oxygen sensor circuit, such as an unexpected or implausible signal. This rear sensor helps fine-tune fueling and monitor the catalytic converter on vehicles that use a third sensor. It's typically resolved by replacing the oxygen sensor, but corroded connectors, damaged wiring, or a poor ground can also cause it.
Common symptoms
- Check engine light is on
- Mildly reduced fuel economy
- Failed emissions or smog test
- Car usually drives normally
- Erratic or stuck oxygen sensor readings on a scan tool
Common causes
- Faulty bank 2 sensor 3 oxygen sensor
- Corroded or loose sensor connector
- Damaged, shorted, or chafed sensor wiring
- Poor ground connection for the sensor
- Exhaust leak near the sensor affecting its readings
Typical repair cost
$150 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0163 code?
Usually yes, since this rear sensor mostly affects emissions monitoring rather than engine performance. Short trips are generally fine, though fuel economy may slip a little. Aim to have it diagnosed within a week or two to keep everything running cleanly.
How much does it cost to fix a P0163 code?
Most repairs land between $150 and $400, covering the oxygen sensor and roughly an hour of labor. If the issue is just a connector or a section of wiring, the cost can be lower. Hard-to-reach sensors on some vehicles can push the price toward the higher end.
Is a P0163 code serious?
It's a moderate concern at most. The vehicle stays drivable and safe, but the code blocks you from passing emissions and can slightly raise fuel consumption. Fixing it promptly is wise but it isn't urgent.
What does Bank 2 Sensor 3 mean?
Bank 2 is the side of the engine that doesn't contain the number one cylinder, and sensor 3 is the third oxygen sensor in the exhaust flow on that side, sitting downstream of the catalytic converter. Only some vehicles use a third sensor, and it's there to keep a closer watch on emissions performance.