The P0137 code points to Bank 1 Sensor 2, the downstream oxygen sensor located after the catalytic converter on the Bank 1 side of the engine.
In practical terms, that sensor is threaded into the exhaust pipe downstream from the catalytic converter and monitors how effectively the cat is reducing emissions. The exact mounting varies by vehicle, but it is always positioned downstream of the catalytic converter on the Bank 1 side.
What P0137 Means
P0137 is an OBD-II diagnostic trouble code indicating a low voltage reading from Bank 1 Sensor 2. This could be caused by a faulty sensor, damaged wiring or connector, a loose connection, exhaust leaks, or issues upstream affecting readings. The location information helps you find the sensor for inspection or replacement.
Locating Bank 1 Sensor 2
Below are common placement scenarios to help you identify the sensor on a wide range of vehicles. The exact spot can vary by model, so use these as a guide and consult your vehicle’s service manual for the precise location.
- Post-cat O2 sensor on a front-wheel-drive, transverse-engine layout: typically mounted in the downpipe just after the catalytic converter, accessible from beneath the vehicle or from the engine bay area.
- Inline or longitudinal engines: Bank 1 Sensor 2 is usually threaded into the exhaust pipe after the catalytic converter, along the downpipe or near the cat housing, reachable from underneath.
- V-configured engines (V6/V8): Bank 1 Sensor 2 sits on the exhaust stream after the catalytic converter on the Bank 1 side, often on the exhaust manifold outlet or the downstream pipe, with the wiring harness routed along the engine or subframe.
In all cases, Bank 1 Sensor 2 is the downstream oxygen sensor located after the catalytic converter on the Bank 1 side. If you cannot locate it by inspection, check the vehicle’s service manual or a repair guide specific to your make and model.
Verification and Safe Access
To confirm you’ve found the correct sensor and to plan safe access, consider these steps:
- Identify Bank 1 using the engine layout or the vehicle’s manual; Bank 1 is the side containing cylinder 1.
- Trace the exhaust pipe downstream from the catalytic converter to locate the sensor mounting point and its connector.
- Look for labeling on the sensor body or wiring harness, often printed as B1S2 (Bank 1 Sensor 2).
- Cross-check with a service diagram for your exact model to avoid confusing Bank 1 Sensor 2 with other O2 sensors.
Proceed with caution: the exhaust system can remain extremely hot after operation. Wear gloves, allow cooling time, and disconnect the battery if you’ll be handling electrical connections.
Summary
P0137 corresponds to Bank 1 Sensor 2, the downstream O2 sensor located after the catalytic converter on the Bank 1 side of the engine. While exact placement varies by vehicle, it is generally found on the exhaust pipe downstream of the catalytic converter. For your specific model, consult the service manual or a reputable repair guide to confirm the precise location and access points.