P0140Severity: Low
P0140 – Oxygen Sensor No Activity (Bank 1 Sensor 2)
No activity detected from the downstream O2 sensor.
What it means
No expected signal from the post-catalyst oxygen sensor. Catalyst efficiency can't be monitored; usually a sensor or wiring issue.
Symptoms
- Check-engine light
- Emissions readiness issues
Common causes
- Faulty downstream O2 sensor
- Heater circuit issue
- Open wiring
- Connector issue
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Frequently asked questions
What does trouble code P0140 mean?
P0140 – Oxygen Sensor No Activity (Bank 1 Sensor 2). No expected signal from the post-catalyst oxygen sensor. Catalyst efficiency can't be monitored; usually a sensor or wiring issue.
Can I drive with a P0140 code?
It's usually not urgent, but finding and fixing the cause matters for emissions and fuel economy.