P0146 Oxygen sensor: no signal (bank 1, sensor 3)
P0146 means: Oxygen sensor: no signal (bank 1, sensor 3). The oxygen sensor measures oxygen in the exhaust and the computer sets the fuel mixture by it. OK to drive, but have it checked soon. The most common repair costs about €45–90 in Estonia, depending on make and model.
What it means
The oxygen sensor measures oxygen in the exhaust and the computer sets the fuel mixture by it. Sensor 1 sits before the catalytic converter, sensor 2 after it. The computer found the signal wrong, slow or missing. The computer gets no signal at all from the part. Sensor 2 or 3 sits after the catalytic converter.
What you may notice
- Engine light on
- Higher fuel consumption
- Idle may be uneven
- Emissions may fail the inspection
What could be wrong
- 1Connector loose, damp or corroded · Wiring or connector repair €45–90
- 2Wire broken or chafed · Wiring or connector repair €45–90
- 3Faulty oxygen sensor · Oxygen sensor replacement €90–180
- 4Engine computer fault (rare) · Control unit check and software €150–300
Repair difficulty: Moderate
What you can check yourself
First look at the connector and wiring: anything loose, melted or green with corrosion? Listen for an exhaust leak ahead of the sensor. Check that the sensor wire is intact and the connector is clipped in. You can do the simpler checks yourself.
How we fix it
- We read the fault data on the diagnostic tool and check whether the fault is constant
- We measure the circuit's supply, ground and signal
- We repair the wire or replace the connector
- If the wiring is fine, we replace the oxygen sensor
Standard SAE description: O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)