Message "check hybrid system"

[Mike Fox]

Driving along the motorway and P/S appears followed by loss of steering and power and message "check hybrid system" . Stopped on hard shoulder switched off ignition, switched on and started engine P/S disappeared but "check hybrid system" message remained.  Car drove normally stopping and starting as normal. 

Following day no messages but after 20 miles or so same thing occurred. Dashboard schematic appeared to show power distribution and hybrid Battery charging and discharging normally. I've now driven 500 miles touring Spain with no other problems. 

Car is a 2006  lexus 400H with 98,000kms. I leave it in our garage in Spain with the Battery disconnected for 3 or4 months at a time. I've done this for 10 years or so without issue. I replaced the 12v Battery last year. 

I'm told it could be a communication issue between the cooling fans and the Ecu. 

Any ideas anyone? 

[ColinBarber]

The first thing you need to do is attach a fault reader to obtain the error code(s) that have been triggered. Until then it is just speculation about which of the 100+ faults that could produce that error has actually occurred.