P0151

O2 Sensor Circuit Low Voltage Bank 2 Sensor 1

Q: Is it safe to drive with P0151?

Yes, short-term. The engine runs on a bad oxygen-sensor signal, so fueling and economy suffer. Repair it before an emissions test and to avoid wasting fuel.

Q: Can I just clear P0151?

It returns within a drive cycle or two unless the sensor, wiring, or underlying lean condition is repaired.

Oxygen sensor (fuel & air) Generic OBD-II Medium

What it means

P0151 means the upstream oxygen sensor on bank 2 (sensor 1) is reporting a persistently low voltage. That points to a faulty sensor or wiring, or a genuinely lean exhaust on that bank. The ECM uses this sensor to trim the air/fuel mix, so the main effects are poorer economy and higher emissions — the engine still runs and starts normally. Bank 2 is the side of the engine that doesn't contain cylinder 1.

Medium

Can I keep driving? Yes — the car runs and starts, but expect worse fuel economy and an emissions-test failure until it's repaired.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

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
Poor fuel economy
Slight hesitation or rough running
Failed emissions/smog test

Common causes

Most likely first

Faulty upstream O2 sensor (bank 2, sensor 1)Likely
Signal wire shorted to ground or open in the O2 circuitCommon
Exhaust leak ahead of the sensor skewing the readingCommon
Genuine lean condition (vacuum leak or low fuel pressure)Less often
Failed ECM/PCM (rare)Less often

How to diagnose & fix

Work through it in order

View the bank 2 sensor 1 O2 voltage and fuel trims in live data to tell a stuck-low sensor from a truly lean engine.
Inspect the O2 sensor wiring and connector for damage or a short to ground.
Check for exhaust leaks near the sensor and vacuum leaks that could cause a lean condition.
Confirm fuel pressure is in spec if trims show a real lean condition.
Replace the O2 sensor if it's faulty. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0151?+

Yes, short-term. The engine runs on a bad oxygen-sensor signal, so fueling and economy suffer. Repair it before an emissions test and to avoid wasting fuel.

Can I just clear P0151?+

It returns within a drive cycle or two unless the sensor, wiring, or underlying lean condition is repaired.

Read & clear P0151 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