P0133 O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
The upstream oxygen sensor on bank 1 switches too slowly between lean and rich.
Common causes
- Aged or contaminated sensor
- Exhaust leak
- Oil or coolant contamination
Symptoms
- Check engine light
- Slightly higher fuel consumption
What to check
- Check sensor switching speed
- Look for exhaust leaks
- Replace an aged sensor
Manufacturers may add their own detail to generic codes. If your vehicle shows a different description for P0133, follow the service information for that make and model.