P0137 code

When it's not one thing on this van it's another. On my way to work this morning my check engine light came on, plugged her in and found a P0137 code showing 02 sensor circuit low, voltage bank 1 sensor. Would this indicate a broken wire or corrosion or??? I am guessing bank 1 would be the left (driver) side????? I cleared the code but would like to stop it from coming back.

Thanks for any help

That would be the left (driver side) upstream sensor. The code indicates a signal below the bias voltage.

If you read the voltage in the circuit at the PCM terminals or back-probe the sensor connector and get zero volts it could be a shorted sensor. If disconnecting the sensor causes the circuit voltage to rise to 350-450 mV it is likely a shorted sensor. If disconnecting the sensor causes no rise in circuit voltage look for shorted wiring or an open circuit at the PCM. Moisture and corrosion in connectors can shunt the signal the same way.

If you are lucky/careful, you can exchange the two sensors and see if the problem moves with the sensor or remains with the wire harness.