P0147 — O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)
Can drive — fix at your convenience.
What P0147 means
This code means the engine computer is seeing no signal activity from the third oxygen sensor on bank 1, as if the sensor is asleep or disconnected. It's usually caused by a failed O2 sensor, broken or unplugged wiring, or a blown sensor heater. It's a common, sensor-related code and is typically fixed by repairing the wiring or replacing the sensor.
Common symptoms
- Check engine light is on
- Slightly reduced fuel economy
- Failed emissions or smog test
- No or flat O2 sensor reading on a scan tool
- Usually no change in how the car drives
Common causes
- Failed oxygen sensor (Bank 1 Sensor 3)
- Broken, open, or unplugged sensor wiring
- Blown fuse or failed sensor heater circuit
- Corroded or loose sensor connector
- Less commonly, an engine control module fault
Typical repair cost
$150 – $450
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0147 code?
For normal use, usually yes. The sensor just stopped reporting, so the car should run and stay reliable. Still, have it checked within a week or two so your emissions system works properly and you can pass a smog test.
How much does it cost to fix a P0147 code?
Most repairs land between $150 and $450, depending on whether it's the sensor, the wiring, or the heater circuit. The sensor and labor are the biggest factors, and hard-to-reach locations cost more.
Is a P0147 code serious?
It's a low-severity code. It won't hurt your engine in the short term, but a non-responsive O2 sensor means worse emissions monitoring and a likely failed smog test, so it's worth fixing soon.
What causes 'no activity detected' from an O2 sensor?
It usually means the sensor signal is flatlined, often because the sensor itself has failed, its wiring is broken or unplugged, or its internal heater isn't working. A technician can quickly check the wiring and sensor heater to pinpoint which it is.