O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 2
Code P2273 indicates that the oxygen sensor (O2S) located after the catalytic converter on Bank 2 (the side of the engine not containing cylinder #1) is reporting a rich air-fuel mixture that is stuck or biased. This means the sensor voltage is consistently high (above 0.6V) and not switching normally, suggesting the sensor is 'seeing' a rich condition or is itself faulty. The ECM monitors the sensor's response and sets this code when the signal remains rich for an extended period, which can be caused by a defective sensor, exhaust leaks, fuel system issues, or engine mechanical problems.
1. Most Common Causes
- Bank 2 Sensor 2 oxygen sensor (HO2S) contaminated, aged, or internally damaged
- Short circuit to voltage in the HO2S signal circuit
- Exhaust leak upstream of the sensor (false rich condition due to Venturi effect)
- Leaking or dripping fuel injector on Bank 2
- Fuel pressure regulator leaking into the intake manifold
- Faulty PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Failed emissions test
- Possible rough idle or hesitation
3. Step-by-Step Diagnosis
Step 1: Scan the vehicle for codes and record freeze frame data.
Step 2: Visually inspect the O2 sensor wiring and connector for damage.
Step 3: Check for exhaust leaks upstream of the sensor using a smoke machine or by listening for hissing.
Step 4: Monitor O2 sensor voltage with a scan tool; if stuck above 0.6V, suspect a rich condition or faulty sensor.
Step 5: Test fuel pressure and inspect fuel injectors for leaks or sticking open.
Step 6: Perform a smoke test for vacuum leaks and check engine compression if other causes are ruled out.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but it may cause poor fuel economy and potential damage to the catalytic converter over time. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY oxygen sensor replacement. Professional diagnosis and repair may cost $100-$300 depending on labor and parts.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.