A 2004 mileage 2. 0L car equipped with K20A7 engine and automatic transmission with a mileage of about 60 thousand km. User response: after the car starts the engine, the dashboard engine fault light has been lit. After the car: test run, confirm that the engine work is basically normal, but the engine warning light has been lit. The car is equipped with the OBD II diagnostic stand, and is diagnosed by using the diagnostic instrument. The result has a fault code 45-1, meaning A/F sensor S1 heater failure. Referring to the relevant information, we know that the A/F sensor is also an oxygen sensor. The engine is equipped with two oxygen sensors, one is the oxygen sensor S1 and the other is the oxygen sensor S2. Remove the fault code, test the car, the fault is still.