P0150 Code: O2 Sensor Circuit (B2S1) — Causes & Fix
P0150 means a malfunction in the upstream oxygen sensor circuit on bank 2, sensor 1 (the second cylinder bank on V-engines).
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $40 – $300
- Time to fix
- 30 minutes – 2 hours
What it means
Causes include an aged/contaminated O2 sensor, an exhaust leak, or wiring/connector faults on bank 2. P0150 is a generic OBD-II powertrain code defined in the SAE J2012 standard, so it applies to virtually any 1996-or-newer petrol car or light truck regardless of make. Fix the underlying fault, then clear the code with an OBD-II scan tool — it will return if the problem isn't resolved.
Symptoms
- Check engine light on
- Worse fuel economy
- Rough running or failed emissions
How to fix it
- 1
Inspect sensor and exhaust
1. Check the bank 2, sensor 1 connector and wiring. 2. Look for exhaust leaks.
- 2
Replace the sensor
1. Replace an erratic upstream bank 2 O2 sensor. 2. Clear the code.
Frequently asked questions
Where is bank 2 sensor 1?
It is the upstream O2 sensor (before the converter) on the bank that does not contain cylinder 1.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.