P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
The upstream oxygen sensor on bank 1 shows no switching activity.
Common causes
- Failed sensor
- Open circuit
- Failed heater keeping the sensor cold
Symptoms
- Check engine light
- Poor fuel economy
What to check
- Check heater and signal circuits
- Inspect connector
- Replace sensor if dead
Manufacturers may add their own detail to generic codes. If your vehicle shows a different description for P0134, follow the service information for that make and model.