P0137 Nissan Sentra
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2) · Powertrain Code · Medium · Repair: Easy
What is P0137?
Low voltage from the downstream O2 sensor on bank 1.
When the Nissan Sentra triggers code P0137 (o2 sensor circuit low voltage (bank 1, sensor 2)), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the Nissan Sentra.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Nissan Sentra.
Common Causes on Nissan Sentra
- Failed downstream O2 sensor (Bank 1 Sensor 2)
- Exhaust leak between catalytic converter and downstream sensor
- Contaminated sensor from oil or coolant in exhaust
- Sensor wiring damage from heat or corrosion
Symptoms
- Check Engine Light on
- Slightly worse fuel economy
- May trigger P0420 if catalyst is also degraded
- Failed emissions test
Notes for Nissan Sentra
If P0137 appears with P0420, diagnose the catalytic converter first; a failed converter can cause downstream sensor issues.