Technical Description of OBD-II Trouble Code
The O2 Sensor Signal on Bank 2 Sensor 2 is Biased or Stuck Rich
What does that mean?
This code is applicable to all OBD-II equipped vehicles manufactured from 1996 onwards. It covers 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 P2273 diagnostic trouble code (DTC) pertains to the post-catalytic converter O2 (oxygen) sensor on bank #2, sensor #2. 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 or biased towards a rich air-fuel mixture, it sets this DTC.
The P2273 DTC refers to sensor #2 on bank #2, which is the side of the engine that does not contain the #1 cylinder. If there is a third sensor downstream and it is causing the problem, a P2277 code will be set.
This code indicates that the particular oxygen sensor is detecting a rich air-fuel mixture (meaning there is too little air in the exhaust). It is not uncommon to see both the P2271 and P2273 codes set simultaneously, depending on the vehicle and the underlying cause of the issue.
A typical oxygen O2 sensor:
Symptoms
You will most likely not experience any drivability issues since this is not sensor #1. However, you may notice that the Malfunction Indicator Lamp (MIL) is illuminated. In some cases, the engine may run rough.
Potential Causes
The potential causes for this DTC may include:
Diagnostic and Repair Procedures
Inspect the wiring and connectors visually for corrosion, rubbed / chafed / bent wires, wiring pins that are bent or loose, burnt appearance, and/or crossed wires. Repair or replace as necessary.
Check for exhaust leaks or other problems and repair them 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. Replace or repair as necessary.
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 show 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 usually 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 buy 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 the fuel injectors, and inspecting the coolant passages for leaks.
