ABS fault code 24098, 240100, 23979

[ksaepert@yahoo.com]

Hello experts,
on my R1200GSA I am getting intermittent fault codes, 24098, 240100 and 23979 together with ABS error light on. Not all codes at the same time though. it is alternating randomly. In case of error, the Pressure circuit reading jumps to 262144 mBar.
Switching of the ignition and resetting with the GS-911 brings it back to normal. Failure appears after few minutes of starting the engine. Breaks are working well, obviously without ABS functionality.
The failure started after the bike was not used for 6 months with the battery disconnected.

Any suggestion other than bleeding or flushing the brake fluid is welcome.