| 摘要 |
PURPOSE: A secondary air valve error diagnosis system for a secondary air inlet device is provided to prevent the exhaust gas from being emitted into the atmosphere by informing the open/shut state of the secondary air valve to the driver. CONSTITUTION: A secondary air valve(5) is mounted at the intermediate portion between an O2 sensor(1) and a catalyst(2) arranged under an exhaust manifold(10) and a secondary air pipe(4) interposed between a secondary air pump(3) and the exhaust manifold. An engine control unit(ECU) diagnoses errors of the secondary air valve in accordance with the oxygen density sensed by the O2 sensor and air-fuel ratio when the secondary air valve is excessively open. A secondary air solenoid(6) is mounted to the secondary air valve, and a contact of a secondary air relay(Ry) operating by the control of the engine control unit is connected to the secondary air pump. The secondary air pump is compulsorily turned off by the control of the engine control unit and a predetermined alarm signal is output to the driver when the secondary air valve is diagnosed as having an error.
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