O2 Sensor Slow Response (Bank 1, Sensor 1)
The upstream oxygen sensor switches between rich and lean too slowly. Aged sensors lose response speed before they fail outright; this code typically appears before P0130/P0131/P0132.
Affected components
- Oxygen sensor upstream
Common causes
- High likelihood: Oxygen sensor aged
- Medium likelihood: Sensor partially poisoned (silicone, lead, sulphur)
Possible symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.