What is the meaning of three-way catalytic bank1?

It is an exhaust purification device that converts CO, HC, and NOx in the exhaust into harmless gases by utilizing the action of a catalyst. It is located before the muffler in the exhaust pipe. Fuel trimming is when the electronic control unit (ECU) controls fuel delivery by increasing or decreasing the time the injectors are open so that the engine achieves an optimal air-fuel ratio (air-to-gasoline mass ratio of 14.7:1). An air-to-air ratio that is too rich means that too much fuel is being delivered, and an air-to-air ratio that is too lean means that too little fuel is being delivered. Causes include air leaks after the MAF sensor, leaks in the PCV system, oxygen sensor failure, exhaust leaks near the oxygen sensor, EGR leaks, MAF sensor failure, dirty fuel filter, insufficient fuel supply from the fuel pump, fuel pressure regulator failure, injector blockage, engine speed sensor failure, electronic control module (PCM or ECM) failure, etc. ) malfunction, etc.