P0142 Code: O2 Sensor Circuit Bank 1 Sensor 3
🟠 Moderate severity · drivable
You can usually drive, but fuel economy and emissions can suffer until the sensor is fixed.
What P0142 means
The oxygen sensor in bank 1, position 3 has a circuit problem. This sensor measures exhaust oxygen after the catalytic converter. The computer cannot read the sensor correctly, which can affect emissions and fuel economy.
Symptoms
- Check engine light on
- Poor fuel economy
- Rough running
- Failed emissions test
Common causes
- most common: Faulty O2 sensor
- common: Damaged wiring or connector
- common: Exhaust leak near the sensor
- less common: Blown fuse for the sensor circuit
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Replace the O2 sensor | Yes | $80–200 |
| Repair the wiring or connector | Yes | $20–80 |
| Fix the exhaust leak | Mechanic | $50–300 |
| Replace the blown fuse | Yes | $5–15 |
Frequently asked questions
Can I drive with P0142?
Yes, usually. The engine will still run, but fuel economy and emissions can suffer until the sensor is fixed.
Where is bank 1 sensor 3?
Bank 1 is the side of the engine with cylinder 1. Sensor 3 is a downstream oxygen sensor, usually after the catalytic converter.
Do I need to replace all O2 sensors?
No. Replace the one that is faulty. A scan tool tells you which sensor has the problem.
Related codes
P0136
P0136 Code: O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
P0143P0143 Code: O2 Sensor Circuit Low Voltage Bank 1 Sensor 3
P0144P0144 Code: O2 Sensor Circuit High Voltage Bank 1 Sensor 3
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.