This diagnostic trouble code indicates the engine computer is not detecting a switching signal from the upstream oxygen sensor on bank 2. This sensor monitors oxygen content in the exhaust to help regulate fuel mixture, and inactivity suggests an electrical open or a dead sensor. The vehicle will typically operate in open-loop mode, ignoring fuel trim adjustments from this sensor.
The heating element or sensing element inside the sensor has failed, preventing signal generation. This is the most frequent cause of no activity codes.
Wires leading to the sensor may be broken, frayed, or shorted due to heat or physical contact. Inspect the harness near hot exhaust components.
Moisture or exhaust chemicals can cause corrosion at the sensor plug, interrupting the signal circuit. Clean or repair the connector terminals as needed.
A leak before the sensor can introduce false air, preventing the sensor from reading accurate oxygen levels. This can mimic a sensor failure.
Extreme rich or lean conditions caused by injectors or pumps may prevent normal sensor voltage switching. Verify fuel pressure and injector operation.
Internal computer failure is theoretically possible but statistically rare compared to sensor or wiring faults. Do not replace the computer without ruling out all external causes.
No, PCM failure is extremely rare for this code; replacing the computer without diagnosing the sensor and wiring first is usually unnecessary.
The vehicle is drivable, but prolonged driving may reduce fuel economy and potentially damage the catalytic converter due to improper fuel mixture.
Bank 2 is the side of the engine without cylinder number 1, and Sensor 1 is the upstream sensor before the catalytic converter.
No, resetting clears the light temporarily, but the code will return once the computer runs its self-tests and detects the inactive circuit again.