Emission control
P0137 — O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
The downstream oxygen sensor on bank 1 (after the catalytic converter) reports a voltage that stays too low. This sensor mainly monitors converter efficiency, so the effect on driving is small.
Common causes
- Aged or failed downstream oxygen sensor
- Exhaust leak near the sensor
- Damaged wiring or connector
- Shorted signal wire to ground
- Catalytic converter problem
Symptoms
- Often none noticeable
- Check engine light
- Failed emissions test
- Slightly higher fuel use in rare cases
How to check
- Check for exhaust leaks before and around the sensor
- Inspect the wiring and connector
- Watch the live sensor voltage with the engine warm
- Replace the sensor if it stays low or flat
Can you keep driving?
Usually safe to drive. Repair it at a convenient time to pass emissions inspection.
Related codes
Frequently asked questions
- What does P0137 mean?
- The oxygen sensor after the catalytic converter on bank 1 reads low voltage.
- Is P0137 serious?
- Usually not for drivability, but it can cause an emissions inspection failure.
General reference information. It does not replace a diagnosis on your own vehicle. The same code can have different causes depending on make, model year and engine; check the manufacturer's documentation or ask a technician with a scan tool.