Have you posted this problem in Lexus CT200h forums? Somebody there might have had the same issue.
Did they reload the firmware? There might be a problem with the computer code that causes this issue. When the car switches from battery to engine poster, the gasoline has to be shut down or started at precisely the right time, or there are problems. Chrysler had a firmware problem with their PHEV Pacifica where the fuel injection ran on a little too long, and raw gas was dumped into the catalytic converter. Fortunately, there were no fires outside the catalytic converters, but the exhaust tube immediately in front of the converter glowed red. Iām not suggesting that your Lexus does exactly this, but giving an example of what can go wrong if the computer code that controls the hybrid drive train goes awry.