Abstract: The invention proposes an engine (11) comprising a catalytic converter (12c), a first probe (120) able to deliver a first signal (Vsp) proportional to the oxygen content of an exhaust gas and installed upstream of the converter, a second oxygen probe (130) downstream of the converter and able to provide a second signal (Vsb), and means (13) for making a diagnosis regarding the operating condition of the converter, characterized in that: the second oxygen probe (130) is of the on/off type and the means (13) are designed to convert the first signal (Vsp) into a third signal (Vspb) of the on/off type and to make the diagnosis on the basis of the second and third signals (Vsb, Vspb).

Abstract: A method for diagnosing the operating condition of an internal combustion engine exhaust gas recycling valve. The method acquires a measurement value of a reference position of the recycling valve at a predetermined time corresponding to a normally closed position of the valve, calculates the difference between the acquired reference value and a reference value acquired during a diagnostic cycle previously carried out, and compares the calculated difference with a threshold value for detecting opening of the valve.

Abstract: A method for diagnosing the operating condition of an internal combustion engine exhaust gas recycling valve. The method acquires a measurement value of a reference position of the recycling valve at a predetermined time corresponding to a normally closed position of the valve, calculates the difference between the acquired reference value and a reference value acquired during a diagnostic cycle previously carried out, and compares the calculated difference with a threshold value for detecting opening of the valve.