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.

Real-world scan data

Seen in

288

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P0157 scans

P0300in 30.2% of scans

P0137in 18.8% of scans

B1209in 17.4% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P0157 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX