The exclusion of EFI engine failure, found that despite the failure phenomenon, the reasons vary, but it was undoubtedly quite typical oxygen sensor, coolant temperature sensor and throttle position sensor fault. They not only have the characteristics of the high failure rate, and the condition of the engine as well.
   
1. Oxygen sensor fault

Malfunctioning oxygen sensor will affect the computer ECU for precise control of air fuel ratio mixture, bringing the engine power, economic decline and deterioration of the exhaust purification. At this point the engine idling prone to instability, lack of fire, shaking breath and increased fuel consumption and so on. Usually the oxygen sensor failure or poor line connection when, ECU will store the memory and warning.

Early damage to the oxygen sensor of factors: use of leaded gasoline, so that the face of lead buildup occurs in the sensor lead "poisoning"; engine repair using silicone sealant, plus gasoline and oil burning compounds containing silicon after the formation of silica, resulting in oxygen sensor failure; sometimes the engine temperature is too high, but also easily lead to early damage oxygen sensors.

The sensor Despite zirconia, titanium dioxide, etc., the detection method, the data are also differences, are presented a universal detection method: Remove the sensor wiring board so that the voltmeter probe touches the sensor end of the connector. First warm the engine in idle state, the voltage meter data should be greater than the reference value (rich mixture occurs when the voltage on the oxygen sensor); then air flow meter adjustment screw to the left, so that the concentration of the mixture changed thin (still maintaining idle), then the voltage should be lower than the baseline table (more dilute mixture occurs under oxygen sensor voltage). Oxygen sensor is damaged, usually should be replaced. Some manufacturers require each vehicle to be replaced after a certain mileage oxygen sensor, the engine will always maintain a good working condition.