Patent ID: 9732692
Date: 2017-08-15
CPC Classifications: F02D

Claim:
1. An apparatus for diagnosing a fuel pressure sensor characteristic fault, comprising: a fuel injector that is opposed to each of a plurality cylinders of an engine and injects fuel directly into each of the cylinders; a high-pressure fuel generator that is driven by the engine and generates high-pressure fuel; a fuel pressure release unit that regulates an upper limit pressure of the high-pressure fuel; a fuel rail that supplies the fuel injector with the high-pressure fuel discharged from the high-pressure fuel generator; a fuel pressure sensor that is opposed to the pressure rail and detects a fuel pressure in the fuel rail; and a characteristic fault diagnosis unit that determines, after a key switch is turned off, whether a predetermined diagnosis execution condition is satisfied, and performs a diagnosis of a characteristic fault in the fuel pressure sensor if the diagnosis execution condition is satisfied, wherein the characteristic fault diagnosis unit determines that the diagnosis execution condition is satisfied at least if an engine temperature immediately before turn-off of the key switch reaches a full warm-up temperature, and if a set key-off time elapses after the key switch is turned off, and wherein if the characteristic fault diagnosis unit determines that the diagnosis execution condition is satisfied, the characteristic fault diagnosis unit determines whether the fuel pressure detected by the fuel pressure sensor is lower than a predetermined tolerance range, and if the fuel pressure is below the tolerance range, the characteristic fault diagnosis unit reads the fuel pressure detected by the fuel pressure sensor after engine start, and if the fuel pressure is higher than a ground fault determination threshold, the characteristic fault diagnosis unit determines that the fuel pressure sensor has a characteristic fault on an under-tolerance side.