O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 2
Code P2273 indicates that the oxygen sensor (HO2S) in Bank 2, position 2 (downstream of the catalytic converter) is reporting a rich air-fuel mixture that is stuck or biased. This means the sensor voltage remains high (above 0.6V) for an extended period, failing to switch normally. The PCM detects this as a fault because the downstream sensor should fluctuate less but still indicate a lean condition after the catalyst. Causes include a faulty sensor, exhaust leaks, fuel system issues, or a failing catalytic converter.
01. Most Common Causes
- Faulty oxygen sensor (Bank 2 Sensor 2)
- Exhaust leak before the sensor
- Fuel pressure or injector issues causing rich mixture
- Faulty catalytic converter
- Engine mechanical problems (e.g., low compression)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Failed emissions test
- Possible rough idle or hesitation
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the O2 sensor wiring and connector for damage.
Step 3: Use a scan tool to monitor O2 sensor voltage; if stuck above 0.6V, suspect rich condition or sensor fault.
Step 4: Check for exhaust leaks upstream of the sensor using a smoke machine or soapy water.
Step 5: Test fuel pressure and inspect for leaking injectors.
Step 6: If all else is normal, replace the Bank 2 Sensor 2 oxygen sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but it may cause poor fuel economy and damage the catalytic converter over time. It's best to diagnose and fix promptly.
How much does it cost to fix?▼
Typically $50-$150 for the sensor plus labor if you DIY; shop labor can add $100-$200.