Can I drive with P0137?

Yes, for short distances. The downstream sensor does not directly control fuel injection, so the car will run normally. Long term, the low signal often masks a developing exhaust leak or converter issue that should be addressed.

Can an exhaust leak cause P0137?

Yes. Even a small leak between the catalytic converter and the downstream sensor lets fresh air reach the sensor, which it reads as a lean exhaust and reports as low voltage. Check for cracked welds, loose clamps, and worn gaskets before replacing the sensor.

Will a bad O2 sensor damage the catalytic converter?

Not the downstream sensor by itself. P0137 alone does not change fuel mixture significantly. But if the underlying cause is a real lean condition or a failing upstream sensor, that can damage the converter over time.

How much does it cost to fix P0137 in Europe?

Replacing the downstream sensor at an independent garage typically costs 90-310 euros including labour, depending on the part and access. A franchised dealer will normally be dearer, largely because of the price of the sensor itself.

P0137: O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)

Quick Answer

Safe to drive (short-term)

P0137 means the downstream oxygen sensor on Bank 1 (post-catalyst, Sensor 2) is reporting a voltage that stays too low for too long. This typically indicates a lean exhaust condition reaching the sensor, an exhaust leak ahead of the sensor, or a failed sensor stuck at low voltage. The downstream sensor should read a relatively steady 0.6-0.8V when the catalytic converter is working properly.

Severity: Moderate · Emissions
Estimated repair cost: From €45 to €310+, varies by vehicle

Scan your own car in about 60 seconds: see whether P0137 is really what it has, how urgent it is, and what the fix should cost. Free on iPhone and Android with an ELM327 adapter (Bluetooth LE on iPhone).

Get Skanyx free

What does P0137 mean?

P0137 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0137 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

What are the symptoms of P0137?

If your vehicle has triggered P0137, you may notice one or more of these symptoms:

Check engine light illuminated
Slight increase in fuel consumption
Possible failed emissions test
Usually no noticeable change in how the car drives
Often appears alongside P0420 if the converter is degrading

What causes P0137?

Here are the most common causes of P0137:

Failed downstream O2 sensor (Bank 1, Sensor 2) stuck at low voltage
: high
Exhaust leak between the catalytic converter and downstream sensor allowing fresh air in
: high
Damaged or corroded O2 sensor wiring or connector
: medium
Catalytic converter degradation reducing oxygen storage capacity
: medium
Actual lean condition reaching the downstream sensor (vacuum leak, low fuel pressure)
: low

Is it safe to drive with P0137?

Generally yes, for short-term driving. Safe to drive short term. The downstream sensor does not directly control fuel mixture, but a persistent low signal often points to a damaged sensor, an exhaust leak, or a degrading catalytic converter. Do not delay repairs beyond a few weeks.

How do you diagnose P0137?

Follow these steps to pinpoint the root cause of P0137:

Read freeze frame data and check for any companion codes (P0420, P0171, P0174) that suggest a lean condition or converter problem
Inspect the exhaust system between the catalytic converter and the downstream sensor for cracks, loose clamps, or leaking gaskets
Inspect the Bank 1 Sensor 2 connector and wiring for corrosion, heat damage, or chafing
Use a scan tool to view downstream sensor voltage. A healthy sensor reads around 0.6-0.8V steady. A reading stuck below 0.2V points to sensor failure or an exhaust leak
Substitute a known-good sensor or swap with the Bank 2 downstream sensor if equipped. If the low voltage follows the sensor, the sensor is faulty

How much does P0137 cost to fix?

Repair costs for P0137 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 1, Sensor 2)	€40–€180	€50–€130	€90–€310	Moderate
Fix exhaust leak near downstream sensor	€15–€90	€60–€200	€75–€290	Moderate
Repair O2 sensor wiring or connector	€5–€25	€40–€120	€45–€145	Moderate

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

Full repair guides

Oxygen Sensor Replacement Cost

P0137 on specific vehicles

P0137 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0137 on BMW

BMW 3 Series

See BMW-specific causes & cost

P0137 on Volkswagen

Volkswagen Golf

See Volkswagen-specific causes & cost

P0137 on Audi

Audi A4

See Audi-specific causes & cost

P0137 on Mercedes-Benz

Mercedes C-Class

See Mercedes-Benz-specific causes & cost

These codes are often seen alongside P0137 or indicate related issues:

Common questions about P0137

Can I drive with P0137?: Yes, for short distances. The downstream sensor does not directly control fuel injection, so the car will run normally. Long term, the low signal often masks a developing exhaust leak or converter issue that should be addressed.
Can an exhaust leak cause P0137?: Yes. Even a small leak between the catalytic converter and the downstream sensor lets fresh air reach the sensor, which it reads as a lean exhaust and reports as low voltage. Check for cracked welds, loose clamps, and worn gaskets before replacing the sensor.
Will a bad O2 sensor damage the catalytic converter?: Not the downstream sensor by itself. P0137 alone does not change fuel mixture significantly. But if the underlying cause is a real lean condition or a failing upstream sensor, that can damage the converter over time.
How much does it cost to fix P0137 in Europe?: Replacing the downstream sensor at an independent garage typically costs 90-310 euros including labour, depending on the part and access. A franchised dealer will normally be dearer, largely because of the price of the sensor itself.

Read our detailed guides

Scan your car with Skanyx to diagnose P0137

Your car logged P0137. Skanyx reads it on a standard OBD2 adapter (Bluetooth LE on iPhone), tells you whether it is safe to keep driving, and shows the €45-€310 repair range so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.