I had that readout recently not certain of actual code - H (history) designation which usually means intermittent - drove the dealer nuts - finally they traced it to a faulty electric unit in drivers door ie power windows,locks,etc.Replaced it under warranty and during road test by service manager it returned - turned out to be a loose electrical connection in the dash. It's been perfect ever since.I don't frankly know if the latter problem was a single cause or I had two problems.Can review with dealer if it assists.