Method for detecting faults in the air system of internal combustion engines

A method for detecting faults in an air system of an internal combustion engine having an intake manifold and an exhaust manifold includes, but is not limited to the steps of measuring an oxygen concentration of the gas flowing in the exhaust manifold, estimating an intake oxygen control value in the intake manifold and estimating an intake oxygen reference value in the intake manifold based on said oxygen concentration of the gas flowing in the exhaust manifold. The method further includes, but is not limited to the steps of calculating an intake deviation value as a difference between the intake oxygen control value and the intake oxygen reference value and verifying if the intake deviation value is greater than a predetermined first threshold.