Technical Description of OBD-II Trouble Code
Code P2277: O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 3
What does that mean?
This is a generic powertrain code that applies to all OBD-II equipped vehicles manufactured from 1996 onwards. This code can be found in various auto brands such as Hyundai, Ford, Jeep, Chevy, BMW, Kia, Holden, Dodge, etc. However, the specific troubleshooting steps may vary depending on the vehicle.
The P2277 diagnostic trouble code (DTC) refers to the oxygen (O2) sensor located after the catalytic converter on bank #2, sensor #3. This sensor is responsible for monitoring the efficiency of the catalytic converter, which is designed to reduce emissions. When the PCM detects that the signal from the O2 sensor is stuck rich or biased rich, it sets this DTC.
The P2277 DTC specifically refers to the second downstream sensor (after the second catalytic converter), sensor #3 on bank #2. Bank #2 refers to the side of the engine that does not contain the #1 cylinder.
This code indicates that the signal emitted by the particular oxygen sensor is stuck rich, meaning there is too little air in the exhaust.
A typical oxygen O2 sensor:
Symptoms
In most cases, you will not experience any drivability issues since this is not sensor #1. However, you may notice the Malfunction Indicator Lamp (MIL) illuminating. In some cases, the engine may run rough.
Potential Causes
The potential causes for this DTC may include:
Diagnostic and Repair Procedures
Visually inspect the wiring and connectors for corrosion, rubbed / chafed / bent wires, wiring pins bent/loose, burnt appearance, and/or crossed wires. Repair or replace as necessary.
Check for exhaust leaks or other problems, and repair as necessary.
Using a digital volt ohm meter (DVOM) set to ohms, check the resistance of the harness connectors. Compare the readings to the manufacturer’s specifications and replace or repair as required.
If you have access to an advanced scan tool, use it to monitor the sensor readings as viewed by the PCM while the engine is running at normal operating temperature in closed loop mode. The rear heated oxygen sensor (HO2S) should normally display a fluctuating voltage between 0 and 1 volt. However, for this DTC, you will likely see the voltage “stuck” at 1V. Revving the engine should cause the sensor’s voltage to change.
The most common fixes for this DTC are typically an exhaust air leak, a wiring problem with the sensor or wiring, or a faulty sensor itself. If you need to replace the O2 sensor, it is recommended to use an OEM one (manufacturer brand) for best results.
If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.
Other troubleshooting ideas include using a fuel pressure tester to check the fuel pressure at the Schrader valve on the fuel rail, inspecting the purge solenoid valve, inspecting fuel injectors, and inspecting coolant passages for leaks.
