P2196 2018 Toyota RAV4 Code - Oxygen Air/Fuel Sensor Signal Stuck Rich Bank 1 Sensor 1

The Air Fuel Ratio (A/F) sensor generates a voltage that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the Engine Control Module (ECM) with feedback so that it can control the air-fuel ratio. The ECM determines the deviation from the stoichiometric air-fuel ratio level and regulates the fuel injection duration. If the air-fuel ratio sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The air-fuel ratio sensor is a planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrow types. The heat generated by the heater is conducted to the solid electrolyte through the alumina, and therefore sensor activation is accelerated.
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.
After the engine has been warmed up, the ECM carries out air-fuel ratio feedback control and maintains the air-fuel ratio at the theoretical level. In addition, after all the preconditions have been met, active air-fuel ratio control is carried out for approximately 10 seconds and during active air-fuel ratio control, the ECM measures the response of the air-fuel ratio sensor by increasing or decreasing a specific injection quantity based on the theoretical air-fuel ratio learned during normal air-fuel control. The ECM determines whether there is an air-fuel ratio sensor malfunction at the mid-point of active air-fuel ratio control.
Under air-fuel ratio feedback control, If the air-fuel ratio sensor output voltage is below 2.8 V (very rich condition) for 5 seconds despite the heated oxygen sensor output voltage being below 0.69 V, the ECM stores Diagnostic Trouble Code (DTC) P2196.

• Faulty Air Fuel Ratio (A/F) Sensor Bank 1 Sensor 1
• Air Fuel Ratio Sensor Bank 1 Sensor 1 harness is open or shorted
• Air Fuel Ratio Sensor Bank 1 Sensor 1 circuit poor electrical connection
• Faulty Engine Control Module (ECM)