O2 Sensor Circuit No Activity / Slow Response (Bank 2 Sensor 2)
The ECU detects no switching or too slow a response from the downstream O2 sensor on bank 2. Often aged or poisoned sensor; downstream sensors usually flat but must respond on diagnostic monitor runs.
Affected components
- Oxygen sensor b2s2
- Oxygen sensor heater circuit
- Catalytic converter bank2
Common causes
- High likelihood: Sensor aged or poisoned
- Medium likelihood: Heater circuit weak
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
Related codes
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.