CodeXOBD

P0150 — O2 Sensor Circuit Malfunction (Bank 2 Sensor 1)

P0150 means the module detected an electrical fault in the upstream oxygen sensor on bank 2. The diagnosis is identical to P0130 but on the opposite bank.

Moderate

The engine runs on default fuel maps for bank 2. Fuel economy suffers and the engine may run unevenly between banks. This code will cause an emissions test failure.

$20–$250Parts, typical range
0.3–1 hLabour
estimateNot a quote · 2026 basis

What P0150 means

On V-configuration engines, bank 2 is the side that does not contain cylinder number 1. P0150 is the bank 2 mirror of P0130. The upstream sensor on this bank has a circuit fault — either a failed sensor, wiring damage, or an exhaust leak near the sensor. The module uses both upstream sensors for fuel trim calculations, so a fault on either bank affects overall fuel control.

Technical summary
SystemEmission control
How the catalytic converter is gradedExhaust leaves the engine, passes the upstream oxygen sensor, then the catalytic converter, then the downstream oxygen sensor. The module compares the two sensor signals: on a healthy converter the downstream signal is steady while the upstream one oscillates. When the downstream signal starts to mirror the upstream one, the converter is judged to have stopped storing oxygen.Engineexhaust outUpstream O₂sets fuel trimCatalytic converterstores oxygenDownstream O₂grades the converterThe module compares the two sensors — that comparison is the test

Symptoms you may notice

What causes P0150

Bank 2 upstream O2 sensor has failed

Very likelylow costeasy

Same failure mode as the bank 1 sensor — degraded sensing element producing a stuck or out-of-range signal.

Wiring or connector damaged on bank 2

Likelylow costeasy

The bank 2 harness runs along the opposite side of the engine and can suffer the same heat and chafing damage.

Exhaust leak near the bank 2 upstream sensor

Possiblelow costmoderate

A manifold or gasket leak on the bank 2 side lets air in near the sensor, skewing the reading and triggering a circuit fault code.

How to diagnose it

1

Confirm which bank is bank 2

Verify which side of the engine is bank 2 — it is the side that does NOT contain cylinder number 1. Misdiagnosing the bank is a common waste of parts.

Tools: Service manualIf it passes: Bank 2 is identified. Continue to step 2.If it fails: Confirm the bank before proceeding.
2

Monitor bank 2 upstream sensor voltage

With the engine warm, watch the sensor voltage. It should oscillate between 0.1V and 0.9V.

Tools: OBD-II scanner with live dataExpected: Oscillating 0.1-0.9VIf it passes: Sensor is responding. Fault may be intermittent.If it fails: Voltage is stuck — replace the sensor.
3

Inspect bank 2 sensor wiring and connector

Check the bank 2 upstream sensor harness for chafing, heat damage, and connector corrosion. Trace the wiring back toward the module.

Tools: Inspection light, MultimeterIf it passes: Wiring is intact. The sensor is confirmed faulty.If it fails: Repair the wiring, clear the code, and re-test.

Related codes

P0130P0151P0152P0153

Common questions

How do I know which side is bank 2?

Bank 2 is the side that does not contain cylinder number 1. On most V6 and V8 engines, cylinder 1 is on the driver side (left side when facing the engine from the front), making bank 2 the passenger side. Always verify with the service manual.

Last verified 2026-07-27 · Sources: SAE J2012 — Diagnostic Trouble Code Definitions and Failure Type Byte (SAE International)

This information is for general guidance and is not a substitute for professional diagnosis. Cost figures are estimates, not quotes.