26.07.2026, 22:22
(26.07.2026, 17:50)secretname@gmx.de Wrote: Dear Freesker Support, or any other expert on the radar system:
can you help on this error code C21A909 for the Radar Module -Front center (MRR)???
It appeared after a front window replacement - and since caused issues (=fully down) of front collission assitant, lane assist, traffic light status indication
DTC report after my recent FCM calibration attached: ECU resets of FCM+Hydra+MRR, finished with a deep sleep . Software versions as well (MRR doesn't show up there)
Is it rather
a) a calibration issue?
or
b) a connection issue of wires/plugs (e.g. water in a plug; or simply plug was disconnected in a repair, but not properly reconnected)?
or
c) even a module hardware failure?
or maybe something completely different?
The interesting thing is that after calibrating the FCM with Freesker tool, the front collission assistant (including braking in close situtations), the lane assist, the traffic light status indicator started working again - so I was wondering how a front collission assistant incl braking could work without the Front center radar module, i.e. I think this module does work actually.
And another interesting thing about the diagnosis of the MRR: when running first time, there's a timeout. When refreshing/running again, it is successful. I was wondering whether this points to an issue with connecting to it. See the last 3 pictures attached
Nevertheless, these warning symbols keep on shining, and the error code C21A909 still remains :-(
Any hint and recommendation what to do next?
Thank you so much in advance!

