I had this issue and my technician told me that there are soft and hard faults for a yellow warning light. In my case as the car was not exhibiting any cut outs or problems, they said to just drive it without racing it to the dealers. If it had been red apparently that would have been worse. In my case they simply reset the fault, took it out for a test and gave it back. Haven't had the problem since (about 400 km ago)