P0137 Honda Civic
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 Honda Civic 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 Honda Civic.
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 Honda Civic.
Common Causes on Honda Civic
- Failed downstream O2 sensor (Bank 1 Sensor 2)
- Wiring damage between downstream O2 sensor and PCM
- Exhaust leak near the catalytic converter outlet
- Deteriorated catalytic converter affecting sensor readings
Symptoms
- Check Engine Light on
- Slight decrease in fuel economy
- May trigger secondary catalyst efficiency codes (P0420)
- Failed emissions inspection
Notes for Honda Civic
Before replacing the downstream sensor, check if P0420 is also stored — if so, the catalyst itself may be the root cause and replacing only the sensor will not fix it.