What's the matter with the Ford Sharp engine lights turning on and off?

Fault phenomenon: A 20 10 3 .5 L Ford Sharp Vehicle has accumulated a mileage of about 20,000 km, and the engine fault light appears. After the engine fault light is on, the vehicle has been driving normally and the engine has not shaken. The owner came to repair it because of the engine fault light. Fault diagnosis: Connect IDS detector to detect the engine system after receiving the car, and the detector displays P0430:00-EC-PCM fault code, indicating that the efficiency of the three-way catalytic converter is lower than the critical value (row 2). After a preliminary inspection of the vehicle, it was found that only the engine fault light was on and there was no other abnormality, so the fault code was cleared and tested, but the engine fault light was not on. Therefore, we can judge the cause of fuel quality and ask the owner about the recent refueling situation. The owner reported that the vehicle had been filled with No.97 gasoline, and recently it was filled with No.93 gasoline at a foreign gas station, and then there was an engine failure light. According to the requirements of Ford Sharp, adding 93 # gasoline can meet the requirements of the car. The analysis may be that there is a problem with the fuel quality of the gas station. It is recommended that the owner continue to add 97 # gasoline for a while. Four days later, the owner reported that the engine fault light was on all the time and the same fault code was detected again. The owner stressed that the vehicle was filled with No.97 gasoline at the designated gas station this time, so the fuel quality was ruled out. Intermittent analysis shows that fuel injector oil leakage, engine circuit failure, gasoline vapor emission control system (EVAP) failure, oxygen sensor failure, and three-way catalytic converter failure may all cause the engine failure light to light up, so the vehicle shall be inspected step by step according to the possibility of failure. Disassemble the fuel rail and spark plug, and find that there is no impurity in the fuel rail and there is no dripping phenomenon in the fuel injector. The color of the spark plug is reddish brown, indicating that the spark plug is normal. Check the appearance of engine wiring, and find that all wiring is exposed, and the connector is connected normally without looseness. Carry out fixed-point test on the vehicle according to the fault code. Check the vehicle OBD system with the detector, and it is normal; No abnormality was found in fuel economy test and power balance test; Through the test, it is found that the evaporation emission of the car is normal; By detecting the value of the oxygen sensor in the engine data stream at idle speed, it is found that the voltage of the oxygen sensor downstream of the vehicle data stream is relatively high, so it can be judged that the internal fault of the three-way catalyst may lead to the engine fault light, because the main function of the downstream oxygen sensor is to detect the working quality of the three-way catalyst. When the second row of three-way catalytic converters was removed, it was found that there was a big hole in the removed three-way catalytic converter. Troubleshooting: After replacing the three-way catalytic converter, test run and troubleshoot, and the engine fault light does not light up when the vehicle is running normally.