The fuel regulation system (mixing ratio) of the rear catalytic converter is too lean (second row).
The fuel regulating system after catalysis is too thin (2nd row)
Category: Fuel, Air or Emission Control
Detailed meaning: Catalytic converter (also called catalytic purification converter) is an exhaust gas purification device which uses the function of catalyst to convert CO, HC and nitrogen oxides in exhaust gas into gases harmless to human body. Generally located in front of the muffler of the exhaust pipe. Fine-tuning of fuel means that the electronic control unit (ECU) controls the fuel delivery by increasing or decreasing the opening time of the fuel injector, so that the engine can obtain the best air-fuel ratio (the mass ratio of air to gasoline is 14.7: 1). Too rich air-fuel ratio means too much oil transportation, and too thin air-fuel ratio means too little oil transportation. Causes of failure include air leakage behind air flow (MAF) sensor, PCV system leakage, oxygen sensor failure, exhaust leakage near oxygen sensor, EGR leakage, air flow (MAF) sensor failure, dirty fuel filter, insufficient fuel supply from fuel pump, fuel pressure regulator failure, fuel injector blockage, engine speed sensor failure, electronic control module (PCM or ECM) failure, etc.