Can I drive with P0158?

Short term yes, but a real rich condition wastes fuel and can clog the bank 2 catalytic converter if it goes on for weeks. If you smell strong fuel from the exhaust or fuel economy has dropped sharply, repair it promptly.

What causes high voltage on the bank 2 downstream sensor?

A genuinely rich exhaust on bank 2 (a leaking injector on that bank, high fuel pressure), a signal wire shorted to voltage, or a contaminated sensor element. Check fuel trims and companion codes before replacing the sensor.

Why would only bank 2 run rich?

Each bank has its own injectors, its own upstream sensor and its own fuel trim. A fault that affects only the cylinders on bank 2, such as one leaking injector, shows up on the bank 2 sensors while bank 1 reads normally. A fault that affects both banks, such as high fuel pressure, usually sets codes on both sides.

How do I know if the catalytic converter or the sensor is bad?

Compare the bank 2 downstream reading with the upstream one. On engines with a switching (narrowband) upstream sensor, a downstream sensor that switches as rapidly as the upstream one means the converter has lost its oxygen storage, and P0430 usually follows. If the downstream sensor is simply stuck high whatever the engine does, the sensor or its wiring is the likely culprit.

P0158: O2 Sensor Circuit High Voltage (Bank 2, Sensor 2)

Quick Answer

Safe to drive (short-term)

P0158 means the Bank 2 downstream oxygen sensor (after the catalytic converter, Sensor 2) is reporting a voltage that stays too high for too long, above roughly 1.0V. Bank 2 is the half of the engine without cylinder 1, found on most V6 and V8 engines, flat-six engines and a few straight sixes with a split exhaust. A healthy downstream sensor reads around 0.6-0.8V steady, so a persistently high reading usually means that bank is running rich, the signal wire is shorted to voltage, or the sensor is contaminated.

Severity: Moderate · Emissions
Estimated repair cost: From €60 to €650+, varies by vehicle

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What does P0158 mean?

P0158 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0158 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 P0158?

If your vehicle has triggered P0158, you may notice one or more of these symptoms:

Check engine light illuminated
Increased fuel consumption
Black smoke or strong fuel smell from the exhaust in severe cases
Possible failed emissions test
May appear with P0175 if bank 2 is genuinely running rich

What causes P0158?

Here are the most common causes of P0158:

Failed downstream O2 sensor (Bank 2, Sensor 2) stuck at high voltage
: high
Actual rich condition on bank 2 (leaking fuel injector on a bank 2 cylinder, high fuel pressure)
: high
Short to voltage in the O2 sensor signal wire
: medium
Contaminated sensor (coolant, oil, silicone sealant)
: medium
Failed bank 2 catalytic converter no longer storing oxygen
: low

Is it safe to drive with P0158?

Generally yes, for short-term driving. Safe to drive short term. A high downstream signal usually points to a rich condition on bank 2, a shorted sensor or a failing catalytic converter. Long-term rich running can clog the bank 2 converter, so do not ignore this for more than a few weeks, and get it checked sooner if you smell fuel from the exhaust.

How do you diagnose P0158?

Follow these steps to pinpoint the root cause of P0158:

Confirm which sensor the code means before buying parts: Bank 2 is the cylinder bank that does not contain cylinder 1, and Sensor 2 is the one after the catalytic converter. Check the cylinder numbering for your engine in the service information, because the side of the car bank 2 sits on is not the same on every engine
Read freeze frame data and check for companion codes (P0175, P0172, P0430) that point to a real rich condition or a converter problem
Use a scan tool to view the downstream sensor voltage. A reading stuck near or above 1.0V at idle indicates a rich condition or a faulty sensor
Compare long-term fuel trims on bank 1 and bank 2. If bank 2 is taking a lot more fuel away (strongly negative, under about -10%), that bank is genuinely running rich
If bank 2 is rich, look at the bank 2 cylinders: misfire counters, injector leakage and spark plug condition on that bank
Inspect the Bank 2 Sensor 2 signal wire for shorts to voltage, especially near heat shields and where the harness runs close to other power wiring
Substitute a known-good sensor. If high voltage persists, the issue is fuel mixture or wiring, not the sensor

How much does P0158 cost to fix?

Repair costs for P0158 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Replace downstream O2 sensor (Bank 2, Sensor 2)	€40–€180	€50–€130	€90–€310	Moderate
Repair shorted O2 sensor wiring	€5–€30	€60–€150	€65–€180	Moderate
Diagnose and fix rich condition (injector, fuel pressure)	€30–€400	€80–€250	€110–€650	Professional
Workshop diagnosis (live data and circuit checks)	€0–€0	€60–€120	€60–€120	Professional

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

Full repair guides

Oxygen Sensor Replacement Cost

P0158 on specific vehicles

P0158 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0158 on BMW

BMW 3 Series · BMW 5 Series

See BMW-specific causes & cost

Mercedes-Benz

Mercedes-Benz E-Class

2005-2011

With separate sensors and fuel trims per bank, an M272 V6 that runs rich only on the left-hand bank (bank 2) raises this sensor's reading while bank 1 stays normal, often with P0175. Check bank 2 fuel trims before condemning the sensor.

P0158 on Audi

Audi A6

See Audi-specific causes & cost

These codes are often seen alongside P0158 or indicate related issues:

Common questions about P0158

Can I drive with P0158?: Short term yes, but a real rich condition wastes fuel and can clog the bank 2 catalytic converter if it goes on for weeks. If you smell strong fuel from the exhaust or fuel economy has dropped sharply, repair it promptly.
What causes high voltage on the bank 2 downstream sensor?: A genuinely rich exhaust on bank 2 (a leaking injector on that bank, high fuel pressure), a signal wire shorted to voltage, or a contaminated sensor element. Check fuel trims and companion codes before replacing the sensor.
Why would only bank 2 run rich?: Each bank has its own injectors, its own upstream sensor and its own fuel trim. A fault that affects only the cylinders on bank 2, such as one leaking injector, shows up on the bank 2 sensors while bank 1 reads normally. A fault that affects both banks, such as high fuel pressure, usually sets codes on both sides.
How do I know if the catalytic converter or the sensor is bad?: Compare the bank 2 downstream reading with the upstream one. On engines with a switching (narrowband) upstream sensor, a downstream sensor that switches as rapidly as the upstream one means the converter has lost its oxygen storage, and P0430 usually follows. If the downstream sensor is simply stuck high whatever the engine does, the sensor or its wiring is the likely culprit.

Read our detailed guides

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