P0163 Code: O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)
🟠 Moderate severity · drivable
Drivable, but the low sensor reading can affect emissions and fuel economy until it's fixed.
What P0163 means
The bank 2 sensor 3 oxygen sensor is sending a voltage that stays too low for too long. A low reading usually means the sensor is failing, its wiring is shorted, or the exhaust stream is unusually lean. This sensor sits after the catalytic converter.
Symptoms
- Check engine light is on
- Failed emissions test
- Slightly worse fuel economy
- Usually no noticeable driving symptoms
Common causes
- most common: Faulty downstream oxygen sensor
- common: Wiring shorted to ground or damaged connector
- less common: Exhaust leak near the sensor
- less common: Engine running lean
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Replace the bank 2 sensor 3 oxygen sensor | Yes | $60–200 |
| Repair or replace damaged wiring and connectors | Yes | $10–60 |
| Fix an exhaust leak or a lean-running condition | Mechanic | $50–300 |
Frequently asked questions
Can I drive with a P0163 code?
Yes, the car is usually safe to drive. It mainly affects emissions and fuel economy, not safety.
What does "low voltage" mean on an O2 sensor?
The sensor signal stays near its low limit instead of swinging normally, which usually points to a bad sensor or a wiring short.
What is the most common cause of P0163?
A failed downstream oxygen sensor, with wiring shorts and exhaust leaks as the next most likely causes.
Related codes
P0162
P0162 Code: O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)
P0164P0164 Code: O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)
P0166P0166 Code: O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.