P0140moderate severityPowertrain
O2 Sensor Circuit No Activity Bank 1 Sensor 2
on 2021 Mazda Mazda3 2.0L I4 · AWD
What this code means
The downstream O2 sensor on Bank 1 shows no switching activity.
Symptoms
- Check Engine Light
- No catalyst monitoring
Common causes
- Faulty sensor
- Heater circuit failure
- Wiring open
Diagnostic steps
- Test sensor voltage
- Check heater
- Inspect wiring
Repair notes
Replace downstream O2 sensor.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1