A couple of summers ago I had a message 'CHECK ENGINE' appear in the message centre after I collected No.146 from a long layup whilst subframe was replaced and other bits and pieces. Having driven gingerly home I looked under the bonnet, checked fluids etc. the engine seemed to be running fine. I began to wonder whether the long layup was causing the message (condensation etc.) so my solution was to disconnect the battery, leave for a few hours and then reconnect. The warning message had gone and has not reappeared. It may not be a solution in your case as the message has reappeared after being cleared but it might be worth a try.

Andrew.