How bizarre, something similar has happened to my car. My display popped up (in white not amber) one dry morning around 7am about two weeks ago, announcing my offside rear sensor missing. As I was on the motorway I changed lanes and looked out for services (if only to get out and kick the tyres) the display stayed like that for about ten mins then one by one the other sensors all disappeared. Now I am thinking it's not a one wheel problem and carried on with my journey with the white display showing a car with no wheels. Approx 20 mins later all the wheels (showing their pressures) came back one by one (reminded me of a computer reboot). It has been fine since and is also working okay with my other set of wheels..
Same thing happened to my Laguna only it was in amber and all the tyres have disappeared and its still not rectified. Where is this TPMS box?? I looked under my car and couldnt really see anything
Any pointers will be appreciated.