Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)

Essentially the same as P0137.

The O2 sensor measures the oxygen levels in the exhaust stream. It registers this with a voltage reading from .1 to .9 mV. The voltage reading is high when the exhaust is rich and low when it is lean. If the computer senses the O2 reading as too high/low for more than two (2) minutes (in most cars) it will come back with a fault.

There may be nothing visible or obvious to the driver something is wrong with it. One indication is poor fuel mileage. This may become increasingly worse over a long period of time so it too may not be obvious.

Possible causes:

  • Faulty O2 sensor leak in exhaust close to O2 sensor
  • Short to voltage on O2 signal circuit
  • Open in circuit resistance caused by corrosion in connector

Possible Solutions:

  • Replace the second oxygen sensor on bank 1
  • Repair open or short in signal circuit
  • Clean corrosion from connector