Failed or aged upstream oxygen sensor on Bank 2; Damaged, chafed or heat-melted sensor wiring or a poor connector; Faulty sensor heater circuit, blown fuse or relay supplying the heater; Exhaust leak near the sensor that skews readings; Contamination of the sensor by oil, coolant or silicone, or a fuel mixture fault on that bank such as a vacuum leak or injector fault; Fault in the engine control unit sensor input circuit.

P0150

O2 Sensor Circuit Bank 2 Sensor 1.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
1: AreaFuel and air metering
50: FaultThe specific fault in that area

What it means

P0150 is the generic code for a malfunction in the oxygen sensor circuit for Bank 2, Sensor 1, which is the upstream sensor ahead of the catalytic converter on the bank without cylinder number one. The engine control unit has seen a signal from this sensor that is out of range, stuck, missing or not switching or responding as expected. Without a reliable signal, the control unit cannot properly trim fuelling for that bank.

Symptoms

Engine warning light on
Poor fuel economy
Rough idle or hesitation
Fuel smell or black smoke from the exhaust
Failed emissions test
Engine running in open loop with uneven fuelling

Possible causes

Failed or aged upstream oxygen sensor on Bank 2likely
Damaged, chafed or heat-melted sensor wiring or a poor connectorlikely
Faulty sensor heater circuit, blown fuse or relay supplying the heaterpossible
Exhaust leak near the sensor that skews readingspossible
Contamination of the sensor by oil, coolant or silicone, or a fuel mixture fault on that bank such as a vacuum leak or injector faultpossible
Fault in the engine control unit sensor input circuitrare

How to diagnose

Read stored and pending codes and the freeze frame data to see engine load, temperature and fuel trims when the fault set, and check for related codes such as heater, fuel trim or misfire faults.
Confirm which side is Bank 2 for this engine, as the layout varies by model, and identify the correct upstream sensor.
Visually inspect the sensor wiring and connector for chafing, melting, corrosion, water ingress or loose pins, particularly near the exhaust.
Check the relevant fuses and relays for the sensor heater circuit using the vehicle wiring diagram.
Look for exhaust leaks upstream of and around the sensor, and for vacuum leaks or other air leaks on that bank.
With a scan tool, watch the live sensor voltage or signal and fuel trims. A healthy sensor switches or responds quickly to enrichment and leaning, while a stuck, flat or slow signal points to a fault.
Test the heater resistance, the supply and ground, and the signal wire continuity back to the control unit against the manufacturer's specifications.
Check for contamination or fuel mixture causes, such as oil or coolant consumption, leaking injectors or fuel pressure faults, if the sensor and wiring test good.

How to fix

Replace the Bank 2 Sensor 1 oxygen sensor if it fails the signal or heater tests.
Repair or replace damaged wiring, terminals or the connector, and secure the harness away from hot or moving parts.
Replace a blown fuse or faulty relay after finding out why it failed.
Repair exhaust leaks near the sensor with correct gaskets or sections.
Fix the underlying mixture, vacuum, oil or coolant problem that contaminated the sensor or upset fuelling.
Where the wiring and sensor are proven good, investigate the control unit input and follow the manufacturer's procedure.

Can I keep driving?

Medium severity

The car can usually be driven short-term, but fuel economy, emissions and the catalytic converter can suffer if the fault is left. Get it checked soon, and stop if the engine runs very rough or smells strongly of fuel.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.