Diagnosis method for ethanol sensor of FFV and FFV operated thereby

A diagnosis method for an ethanol sensor (106) of a flexible fuel vehicle, the flexible fuel vehicle having a fuel refilling detection device (105) disposed in a fuel tank (104), the ethanol sensor (106) disposed on a fuel supply line (101), and an oxygen sensor (107) disposed on an exhaust gas emission line (102), the diagnosis method comprising:

• a) the fuel refilling detection step (S110 of detecting whether fuel is filled to the fuel tank (104) through the fuel refilling detection device (105) disposed in the fuel tank (104);
• b) the maximum changeable content range calculation step (S120) of calculating a content range of ethanol in the fuel stored in the fuel tank (104) on the basis of whether the fuel refilled is pure gasoline or pure ethanol;
• c) the ethanol sensor value acquirement step (S130) of calculating an amount of ethanol remaining on a line between the fuel tank (104) and the ethanol sensor (106), calculating time during which the fuel refilled reaches the ethanol sensor (106), and after the calculated time is elapsed, determining whether the data detected from the ethanol sensor (106) converges into a given value;
• d) the oxygen sensor value acquirement step (S140) of calculating an amount of exhaust gas remaining on a line between an engine (103) and the oxygen sensor (107), calculating time during which the exhaust gas of the fuel refilled reaches the oxygen sensor (107), and after the calculated time is elapsed, determining whether the data detected from the oxygen sensor (107) converges into a given value;
• and
• e) the ethanol sensor abnormality determination step (S150) of determining that an error is generated from the ethanol sensor (106) if the data acquired at the ethanol sensor value acquirement step (S130) or the data acquired at the oxygen sensor value acquirement step (S140) is not a value in the calculated range.