P0137 - OXYGEN SENSOR CIRCUIT LOW VOLTAGE (B1 S2)

Basically this diagnostic code refers to the second oxygen sensor in bank 1. It indicates that the voltage of said sensor remains low for a long time. The ECM (Engine Control module) interprets this reading as a low voltage condition and thus establishes the MIL light.

The second sensor is at the rear of the catalytic converter and has the objective of producing an output signal, which is relative to the oxygen storage capacity of the catalytic converter. Although this signal sent by the O2 sensor is less active than the one sent by the front sensor, when the Engine Control Module detects that the sensor is not active, this code is established.

There can be no symptoms visible to the driver, except that:

• The Check Engine light is on.
• A high fuel consumption.

A code P0137 can have one or more of the following problems:

• Oxygen sensor 2 of the catalyst is bad.
• There may be an escape leak near the rear sensor of the Catalytic Converter.
• The catalyst can be clogged.
• There is a voltage short circuit in the O2 signal circuit.
• There is a motor misfire.
• Fuel pressure is too low or too high.

To fix the DTC code P0137 you can check the following components:

• Replace the defective sensor.
• In case a leak is found in the exhaust, repair it.
• Check that the catalyst does not have any obstruction and, if so, clean. If the failure continues, change it.
• Repair any short resistance, whether open or high, in the O2 signal circuit.