What Does P2273 Mean?
The rear oxygen sensor on Bank 2 (opposite side from cylinder #1) is reading a consistently rich fuel mixture. This post-catalytic converter sensor monitors catalyst efficiency and should show relatively stable voltage if the catalyst is working properly.
Common Causes
45%
Faulty oxygen sensor (contaminated, aged, or failed heater circuit)
25%
Damaged or corroded wiring/connector to O2 sensor
15%
Exhaust leak near sensor affecting readings
10%
Failing catalytic converter causing abnormal readings
5%
Engine running rich on Bank 2 (fuel trim issue)
Diagnostic Steps
1
Step 1: Inspect O2 sensor wiring and connector for damage, corrosion, or oil contamination
2
Step 2: Check for exhaust leaks near Bank 2 Sensor 2 location using visual inspection and smoke test if needed
3
Step 3: Monitor live data for Bank 2 Sensor 2 voltage and response time; verify sensor switches properly
4
Step 4: Check fuel trims for Bank 2 to determine if engine is actually running rich
5
Step 5: Replace O2 sensor if all wiring and fuel trims are normal and sensor shows sluggish response
Estimated Repair Cost
$150 - $400
Parts + labor, varies by vehicle and location
The rear oxygen sensor on Bank 2 (opposite side from cylinder #1) is reading a consistently rich fuel mixture. This post-catalytic converter sensor monitors catalyst efficiency and should show relatively stable voltage if the catalyst is working properly.
The most common cause of P2273 (O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 2) is: Faulty oxygen sensor (contaminated, aged, or failed heater circuit)
Typical repair costs for P2273 range from $150 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but may experience reduced fuel economy and increased emissions. Prolonged operation may damage the catalytic converter.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2273 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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