OBD-II code P2275 indicates that the powertrain control module (PCM) has detected that the oxygen sensor signal for Bank 1 Sensor 3 is biased or stuck in a rich state. This sensor is located downstream of the catalytic converter, and a stuck rich reading usually means the sensor itself has degraded internally or its signal is being affected by exhaust leaks, contamination, or wiring issues.
The oxygen sensor itself has internally degraded or failed, causing its voltage signal to remain stuck in a rich state regardless of actual exhaust gas composition.
An exhaust leak upstream of or near the sensor can introduce outside oxygen, disrupting the sensor's readings and causing biased data.
Corrosion, chafing, or loose connections in the sensor's signal or heater circuit can alter the voltage reading received by the PCM.
Coolant, silicone, or heavy carbon fouling can coat the sensor element, preventing it from accurately reading oxygen levels and biasing it rich.
If the engine is running excessively rich due to leaking fuel injectors or faulty upstream sensors, the downstream sensor may report rich, though this is usually accompanied by other codes.
The engine computer has an internal failure in the monitoring circuit for this specific sensor. This is extremely rare.
Generally, yes, but you may experience decreased fuel economy and you will likely fail an emissions test. It is best to diagnose and repair it promptly to avoid potential catalytic converter damage if the engine is genuinely running rich.
Not necessarily. This code specifically points to the oxygen sensor signal being biased rich. While a failing catalyst can affect sensor readings, this code is far more commonly caused by a degraded sensor, wiring issue, or exhaust leak.
No, replacing the PCM is almost never the correct fix for P2275. Drivers are sometimes mistakenly told to replace the PCM when the actual cause is a degraded oxygen sensor, contamination, or a wiring fault. The PCM should only be considered after all other possibilities are thoroughly tested.
It is a downstream sensor. Sensor 3 is typically located after the primary catalytic converter on Bank 1 (the side of the engine containing cylinder 1).