P0157
O2 Sensor Circuit Low Voltage Bank 2 Sensor 2
Fuel & air metering (O2 sensor)
Generic OBD-II
Medium
What it means
P0157 means the downstream oxygen sensor on bank 2 (after the catalytic converter) is reporting an abnormally low voltage — a lean signal. Because this sensor monitors the converter rather than controlling fuel, the engine drives normally. It usually points to a failed sensor, a wiring open or short to ground, or an exhaust leak near the sensor.
Medium
Can I keep driving? Yes — this is the downstream (post-catalyst) sensor on bank 2, so the car drives normally; it mainly affects emissions monitoring, but have it checked so a real exhaust or fuel issue isn't masked.
Common symptoms
What you'll notice
- Check-engine light on (often the only symptom)
- Slightly worse fuel economy in some cases
- Fails an emissions test
Common causes
Most likely first
- Failed downstream oxygen sensor (bank 2, sensor 2)Likely
- Wiring or connector shorted to ground, open, or corroded (check the fuse too)Common
- Exhaust leak near the sensor drawing in airCommon
- Faulty ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame and live O2 data to confirm the low voltage.
- Inspect the sensor connector and wiring for damage, corrosion, or an open; check the related fuse.
- Check for exhaust leaks ahead of the sensor.
- Replace the downstream O2 sensor if it tests faulty.
- Clear the code and re-test.
FAQ
Quick answers
Is it safe to drive with P0157?+
Yes. Bank 2 Sensor 2 sits after the catalytic converter and doesn't control fueling, so drivability is normal. Fix it so the emissions monitor works and to pass inspection.
Can I just clear P0157?+
It returns unless the sensor or wiring is repaired. Clearing only confirms whether the fault is current or was a one-time event.
Related codes
Often seen with P0157
Read & clear P0157 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX