P0140 — O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
Category: Powertrain Severity: Low
Updated:
DTC code P0140 means: O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2). It falls under the "Powertrain" category, with an estimated severity of Low. Common causes include failed downstream sensor, open sensor heater and disconnected or damaged connector; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Failed downstream sensor
- Open sensor heater
- Disconnected or damaged connector
- Broken wire
Symptoms
- Check engine light
- No noticeable symptoms
How to diagnose it step by step
- Check the connector.
- Measure the heater.
- Watch the signal when warm.
- Replace the sensor.
How to fix it
Check the downstream sensor connector (often exposed under the car) and heater. If both are fine, replace the sensor.
Estimated repair cost
$100–280.
Frequently asked questions
What does DTC code P0140 mean?
O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2).
Is code P0140 serious?
Severity Low. Usually a minor fault; check the causes listed.
Can I keep driving with code P0140?
Yes, it is safe to drive.
Related codes
P0141 P0139 P0138 P0137 P0136 P0135 P0134 P0133 P0132 P0131
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