It's a failure that can be caused by two height sensors giving weird readings, or it could just be that the calibration has become corrupted. If the sensors give what appear to be bizarre readings for heights, the system assumes it's gone wrong and sticks the car on its belly. This being the safest ride height - you wouldn't want to be whizzed up to super extended mode at high speed, for example, as it could become unstable.

If your fault reader can do live values, it would be useful to see the four ride height readings. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

I have iidtool so will check live values
Thanks for the reply

You can check the calibration too, of course, with the IIDTool.

Remember that the values in the calibration aren't actual dimensions in mm, they're just values that the sensors work through. So your calibration can look very odd with each corner showing very different values. It's what they do when working that will be helpful to you. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

I’ve had a quick look at the live value features for the suspension but there are so many different live values to look at do you know which would be the 1 to look at
Thanks
Cosmo