Re-acquired the Launch x-341 scanner and cleared the codes again, as last week. Car started. Drove the car to reduce battery capacity from full, to 4 bars used, with air-con & heating on. Everything works fine. Lights/ windscreen wipers/ heater fan/ electric windows/ there ere no issues with anything. So stoped the car & turned off. Had a cup of tea, went back to start car, and yellow icar fault returned, so no-go.
Re-scanned the codes, faults logged are :- the EV-ECU system showed 3 faults = P1B09 (MCU CAN Timeout/Not Equipped) P1A15 (High Voltage Circuit ) P1A16 (High Voltage Circuit). the KOS/Immo/Keyless system showed 1 fault = U1111 (Display CAN Timeout/Not Equipped), the Meter system showed 1 fault = U1116 (KOS CAN Timeout/Not Equipped. the ETACS system showed 1 fault = U1111 (Display CAN Timeout/Not Equipped) coincidentally this is the same as the KOS system. So if I re-clear all the faults, the car works perfectly. Stop the car, turn it off and when I turn it back on the yellow icar fault returns, and the vehicle is bricked. Done this 4 times now, obviously the answer is, don't turn the car off
The only other obvious thing I can see, is that the fuel bar display is slow to fill when the fault is showing, whereas it is instant when the fault is cleared.
MY BEST GUESS IS, CORROSION ON A CONNECTION SOMEWHERE.