What Does P2277 Mean?
The third oxygen sensor on Bank 2 is reading a consistently rich fuel mixture. This post-catalyst sensor should show stable readings if the emissions system is functioning properly.
Common Causes
45%
Failed or contaminated oxygen sensor
25%
Corroded or damaged sensor wiring/connector
15%
Catalytic converter failure or contamination
10%
Rich fuel condition on Bank 2
5%
Exhaust leak affecting sensor signal
Diagnostic Steps
1
Step 1: Visually inspect O2 sensor for damage, contamination, or excessive carbon buildup
2
Step 2: Check wiring harness and connector for corrosion, fraying, or loose connections
3
Step 3: Monitor Bank 2 Sensor 3 live data for voltage patterns and response time
4
Step 4: Review Bank 2 fuel trim data to determine if engine is running rich
5
Step 5: Replace oxygen sensor if wiring checks good and sensor shows abnormal operation
Estimated Repair Cost
$150 - $400
Parts + labor, varies by vehicle and location
The third oxygen sensor on Bank 2 is reading a consistently rich fuel mixture. This post-catalyst sensor should show stable readings if the emissions system is functioning properly.
The most common cause of P2277 (O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 3) is: Failed or contaminated oxygen sensor
Typical repair costs for P2277 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 will have elevated emissions and reduced fuel economy. May damage catalytic converter if left unrepaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2277 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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