ok it left the factory with the UJN tpms option (auto learn)
This is the learn parameters,but i agree it's probably either the sensors or tpms module at fault
Auto Learn RPO-Code „UJN“
The tyre pressure sensors are automatically learned to the vehicle after any wheel or wheel set change by the additional auto-learn module (ALM). To initiate the learn procedure, the vehicle has to be left standing still for 20 minutes with the ignition off (sensors go into sleep mode) and afterwards by performing a learn drive of approx. 10 minutes in a speed range between 25 to 60 mph.
On vehicles before model year 2014, it may take up to 20 minutes, until a fault is detected. If within 15 consecutive ignition cycles no successful learning process could be performed, the message "Winter Mode" will appear in the Driver Information Centre (DIC) and dashes (---) will be displayed instead of the pressure. If the winter mode is detected, TPMS is disabled
The nominal pressures (Light, Eco or Max) are stored in the body control module. According to the adjusted tyre pressures, the correct load condition has to be selected in the instrument.
Prior to any repair attempts, it´s absolute necessary to check, whether the issue
is a tyre pressure warning or a system fault.
TPMS telltale is illuminated permanent after switching ignition on:
A tyre pressure warning is shown due to low pressure being detected on one or several tyres.
If vehicle is equipped with an instrument with DIC, a message dedicated to the faulty tyre(s) is shown. System works, as it should.
Check tyre pressures. If all tyre pressures are OK, check system settings.
TPMS telltale is initially flashing for 90 seconds and then illuminated permanent after switching ignition on:
A system fault is present. If vehicle is equipped with an instrument with DIC, the message “check TPMS system“ is shown.