Found this in a reasonably recent post on here and it was exactly what I needed:
Copied from rosstech:
Pressure Monitoring System Reset
This procedure will NOT apply unless the vehicle has ABS based Tire Pressure Monitoring (PR-7K1/7K6) installed!
Prerequisites:
Ignition ON
[Select]
[03 - Brake Electronics]
[Basic Settings - 04]
Group 042
[Go!]
Activate the Basic Setting.
[ON/OFF/Next]
[Done, Go Back]
[Close Controller, Go Back - 06]
The Tire Pressure Monitoring Lamp (K220) should blink.
Now check the Tire Pressure and correct it if necessary.
Press and Hold the Tire Pressure Monitoring Button (E492) AND the ASR/ESP Button (E256) for 2 Seconds.
A short Tone should sound after pressing/holding these buttons for 2 Seconds and the blinking should change to a permanent lit Tire Pressure Monitoring Lamp (K220).
The Reset is now done and as soon as you let the buttons go the Tire Pressure Monitoring Lamp (K220) should go OFF.
Did this and warning light on instrument cluster is gone.
I still have the fault in the CAN gateway but I've no idea what it's referring to. It doesn't seem to be affecting anything.
I've got 8 out of the 12 buttons on the steering wheel working, but possibly cant get them all to work as I only have a midline MFD.