P014A - O2 Sensor Delayed Response - Rich to Lean (Bank 2 Sensor 2)

P014A is set when the Engine Control Unit (ECU) monitors the downstream Oxygen (O2) sensor on Bank 2 and determines that the transition time from a rich to a lean state is slower than a predetermined threshold. While upstream sensors (Sensor 1) oscillate rapidly to control air-fuel ratio, downstream sensors (Sensor 2) should maintain a relatively steady voltage. However, during specific events like deceleration fuel cut-off, the ECU expects a rapid drop in voltage. A delay indicates a degraded sensor element, often due to carbon fouling, silicone poisoning, or age-related increase in internal resistance.