F20 Flat Tyre Monitor (FTM?) malfunction (no pressure sensors in tires)

[spude]

Hi all,

New in the forum (and new in diagnosing these newer BMWs with ISTA, just started to learn), hoping to find some help. I have an issue with our 2015 F20 120xDa - the tire pressure monitor malfunction. Basically the warning light in the dash is ON, and the car complains during ignition that the tyre pressures cannot be monitored. Very rarely the light goes away and might stay away for few drives, but then comes back again. The car doesn´t have pressure sensors in the wheels, so it´s indirect monitoring system based on wheel speed sensors (named FTM I guess?). DSC and ABS work as usual.

I bought an ENET cable and read fault codes with ISTA:

DSC_25 DSC-CT01-DSC 0x48069E Tyre Pressure Monitor: wheel recognition when starting, calibration not possible 0 Yes --- <----- (this is the only active fault code)
DSC_25 DSC-CT01-DSC 0x4806B8 Tyre Pressure Monitor: Front left wheel electronics, no reception 105943 Unknown --- <---- (our car does not have these electronics, I assume?)
DSC_25 DSC-CT01-DSC 0x4806DA Tyre Pressure Monitor: wheel electronics, no reception, front right 105943 Unknown ---
DSC_25 DSC-CT01-DSC 0x4806F0 Tyre Pressure Monitor: wheel electronics, no reception, rear left 105943 Unknown ---
DSC_25 DSC-CT01-DSC 0x4806F4 Tyre Pressure Monitor: wheel electronics, no reception, rear right 105952 Unknown ---

I was kinda puzzled with these results, as the suggested services by ISTA were mostly for cars with active tyre pressure monitoring. I could not find any solutions/suggestions for the inactive monitoring system. I´m guessing that there is no separate module (such as RDC) in this car (because there are no sensors). So is it the module responsible for DSC that calculates the tire pressures and has failed? Or any other thoughts?

Thanks!