[BMdriver]

A while back a red warning symbol appeared on the dash to say the tyre monitor was faulty, all tyre pressures were ok, so I re initialised it, all 4 corners went green and the warning light disappeared. To check this is still working, I removed half of the air out of a rear tyre, however when driving it failed to alert me to this. I now fear it is not working, yet the check control says there are no faults. Has anyone else had a similar experience?

Thanks in advance.