Which sensor is Bank 2 Sensor 1?

It is the upstream oxygen sensor, the one before the catalytic converter, on the half of the engine that does not contain cylinder 1. Most V6, V8 and flat-six (boxer) engines have two cylinder banks, each with its own upstream sensor. A few inline-sixes with two exhaust manifolds, such as BMW's M54, also split into bank 1 (cylinders 1-3) and bank 2 (cylinders 4-6). Which physical side is bank 2 differs between makers, so check the service information for your engine before you order a part.

Is P0150 the same as P0130?

It is the same fault on the other side of the engine. P0130 is the upstream sensor circuit on bank 1, the bank with cylinder 1, and P0150 is the upstream sensor circuit on bank 2. If both codes appear together, suspect something the two sensors share, such as a fuse, a ground or the engine computer, before replacing two sensors.

Can I drive with a P0150 code?

Yes, for short distances. The engine keeps running, but bank 2 runs on a default mixture, so expect higher fuel consumption, and the car can be rejected at an emissions test (rules vary by country). A mixture that stays rich for months can overheat and damage the catalytic converter, so book the repair within days, not months. Stop driving if the check engine light flashes.

Should I replace both upstream O2 sensors?

It is not required. P0150 only concerns the bank 2 sensor. On a high-mileage car with both original sensors, doing them together can save a second labour charge, but a bank 1 sensor that still switches normally on live data does not need replacing.

Why does my four-cylinder car show P0150?

A four-cylinder engine with a single upstream sensor has only one bank as far as the engine computer is concerned, so a genuine bank 2 sensor fault is not possible on it. Re-read the code with a second tool and check whether it is actually P0130, the bank 1 equivalent. Some scan tools also mislabel codes on cars they do not fully support.

P0150: O2 Sensor Circuit Malfunction (Bank 2, Sensor 1)

Quick Answer

Safe to drive (short-term)

P0150 means the engine computer is getting an implausible or out-of-range signal from the upstream oxygen sensor on bank 2, the sensor before the catalytic converter on the half of the engine that does not contain cylinder 1. Bank 2 exists on most V6, V8 and flat-six engines and on a few inline-sixes whose exhaust is split into two halves, such as BMW's M54. It is the same fault as P0130, just on the other side of the engine, and the cause is usually the sensor itself or its wiring and plug.

Severity: Moderate · Emissions
Estimated repair cost: From €45 to €560+, varies by vehicle

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What does P0150 mean?

P0150 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0150 and illuminates the check engine light.

Where it is on the car

Engine
Oxygen sensor before the converter (sensor 1)
Catalytic converter
Oxygen sensor after the converter (sensor 2, or 3 on some cars)
Silencer and tailpipe

This code is for bank 2. V6, V8 and flat engines have two cylinder banks, each with its own converter and sensors; bank 2 is the side without cylinder 1.

What are the symptoms of P0150?

If your vehicle has triggered P0150, you may notice one or more of these symptoms:

Check engine light on
Higher fuel consumption than usual
Rough or uneven idle once the engine is warm
Hesitation or flat spot under light acceleration
Out-of-range lambda or CO readings at an emissions test
Often no noticeable change in how the car drives

What causes P0150?

Here are the most common causes of P0150:

Failed or aged upstream O2 sensor on bank 2
: high
Corroded, loose or heat-damaged connector at the bank 2 sensor plug
: medium
Chafed, melted or broken wiring between the bank 2 sensor and the engine computer
: medium
Exhaust leak ahead of the bank 2 sensor (manifold gasket, cracked manifold, loose flange)
: medium
Universal splice-in replacement sensor with poor crimps or the wrong signal characteristics
: low
Sensor contaminated by oil burning, coolant or silicone sealant
: low
Engine computer or its ground connection faulty
: low

Is it safe to drive with P0150?

Generally yes, for short-term driving. You can usually drive to a workshop. Without a usable signal from this sensor the engine runs bank 2 on a default mixture, so fuel use goes up and a mixture that stays rich can damage the catalytic converter over time. If the check engine light starts flashing or the engine misfires, stop driving and have it checked.

How do you diagnose P0150?

Follow these steps to pinpoint the root cause of P0150:

Read all stored codes and the freeze frame. Note whether bank 1 sensor codes (P0130-P0135) or other bank 2 codes (P0151-P0155, P0174) are stored too. Faults on both banks at once point to something they share, such as a fuse, a ground or a fuel or air problem, rather than one bad sensor
Find out which physical side is bank 2 on your engine. It is the bank without cylinder 1, but makers place cylinder 1 on different sides, so check the service information instead of guessing
Warm the engine fully and watch the Bank 2 Sensor 1 and Bank 1 Sensor 1 readings side by side on a scan tool. A healthy narrowband sensor switches between about 0.1 and 0.9 volts several times a second at 2000 rpm. If bank 1 switches and bank 2 is flat, missing or pinned, the problem is on the bank 2 side. Wideband sensors show lambda or current instead of a switching voltage, so compare bank 2 against bank 1
Inspect the bank 2 sensor connector and wiring along its full run for corrosion, melted insulation, pushed-back pins and chafing against the exhaust or heat shields
With the key on and engine off, back-probe the harness plug: confirm battery voltage on the heater feed, a good ground, and continuity of the signal wire back to the engine computer using the wiring diagram
Check for exhaust leaks ahead of the sensor. A ticking noise on a cold start that fades as the engine warms often means a leaking manifold gasket or a cracked manifold
If the wiring and exhaust are sound, fit a direct-fit sensor with the correct plug, clear the code and complete a drive cycle to confirm it stays off

How much does P0150 cost to fix?

Repair costs for P0150 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Replace upstream O2 sensor (Bank 2, Sensor 1)	€40–€180	€50–€140	€90–€320	Moderate
Repair O2 sensor wiring or connector	€5–€25	€40–€120	€45–€145	Moderate
Repair exhaust leak ahead of the bank 2 sensor	€15–€80	€50–€200	€65–€280	Moderate
Replace upstream O2 sensors on both banks at once	€80–€360	€80–€200	€160–€560	Moderate

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

Full repair guides

Oxygen Sensor Replacement Cost

P0150 on specific vehicles

P0150 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0150 on BMW

BMW 3 Series (E46 325i/330i) · BMW 5 Series (545i/540i/550i)

See BMW-specific causes & cost

P0150 on Mercedes-Benz

Mercedes-Benz C-Class (V6)

See Mercedes-Benz-specific causes & cost

P0150 on Porsche

Porsche Boxster (986)

See Porsche-specific causes & cost

These codes are often seen alongside P0150 or indicate related issues:

Common questions about P0150

What does P0150 mean?: P0150 means the engine computer has flagged a problem in the circuit of the upstream oxygen sensor on bank 2. The signal is missing, implausible or outside the range the computer expects. Until it is fixed, the engine cannot fine-tune the fuel mixture on that bank, so fuel economy and emissions suffer.
Which sensor is Bank 2 Sensor 1?: It is the upstream oxygen sensor, the one before the catalytic converter, on the half of the engine that does not contain cylinder 1. Most V6, V8 and flat-six (boxer) engines have two cylinder banks, each with its own upstream sensor. A few inline-sixes with two exhaust manifolds, such as BMW's M54, also split into bank 1 (cylinders 1-3) and bank 2 (cylinders 4-6). Which physical side is bank 2 differs between makers, so check the service information for your engine before you order a part.
Is P0150 the same as P0130?: It is the same fault on the other side of the engine. P0130 is the upstream sensor circuit on bank 1, the bank with cylinder 1, and P0150 is the upstream sensor circuit on bank 2. If both codes appear together, suspect something the two sensors share, such as a fuse, a ground or the engine computer, before replacing two sensors.
Can I drive with a P0150 code?: Yes, for short distances. The engine keeps running, but bank 2 runs on a default mixture, so expect higher fuel consumption, and the car can be rejected at an emissions test (rules vary by country). A mixture that stays rich for months can overheat and damage the catalytic converter, so book the repair within days, not months. Stop driving if the check engine light flashes.
Should I replace both upstream O2 sensors?: It is not required. P0150 only concerns the bank 2 sensor. On a high-mileage car with both original sensors, doing them together can save a second labour charge, but a bank 1 sensor that still switches normally on live data does not need replacing.
Why does my four-cylinder car show P0150?: A four-cylinder engine with a single upstream sensor has only one bank as far as the engine computer is concerned, so a genuine bank 2 sensor fault is not possible on it. Re-read the code with a second tool and check whether it is actually P0130, the bank 1 equivalent. Some scan tools also mislabel codes on cars they do not fully support.

Read our detailed guides

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