In addition to the service interval counter there is also an oil change one. If the oil change counter is not reset eventually the vehicle will go into limp mode.
My handbook says "ENGINE OIL DETERIORATED (MultiJet versions with DPF only) The warning light starts to flash together with a message on the display (for versions/markets, where provided) when the system detects that the engine oil has deteriorated. If the warning light flashes, this does not mean that the vehicle is faulty, but simply informs the driver that it is now necessary to change the engine oil as a result of regular vehicle use. If the oil is not changed, when a second deterioration threshold is reached, the warning light also switches on in the instrument panel and the engine operation is limited to 3000 rpm. If the oil is still not changed, when a third deterioration threshold is reached, the engine is limited to 1500 rpm to avoid damage".
Check the oil change interval by selecting MODE with the ignition ON and select SERVICE. You can then toggle between the service interval and the oil change interval.