| abstract |
(57) [Problem] To provide a failure detection device in a deceleration cylinder-stop engine vehicle that can reliably detect a failure by mainly monitoring the hydraulic pressure of hydraulic oil. SOLUTION: The hydraulic pressure of hydraulic oil is applied to a cylinder-deactivated side path to close both an intake valve and an exhaust valve to stop some cylinders, and the hydraulic pressure of hydraulic oil is relatively applied to a cylinder-deactivated side path. A deceleration cylinder-stop engine vehicle capable of releasing both the intake valve and the exhaust valve in the closed state by releasing the POIL sensor that detects the hydraulic pressure of the cylinder-release-side path; Hydraulic condition determining means (steps S204, S212) for determining whether or not a condition of a hydraulic oil pressure threshold value in each vehicle operating state is provided. An abnormality determining means (steps S207 and S215) for determining an abnormality when it is determined that the condition is not satisfied is provided. |