Club Car 2015 EX 40 Motor won't Start

I have Club Car Golf Cart. It will turn over but the motor will not run. It comes up with a fault code of 31 which sho on my searches as fairly open ended. Does anyone know what I have to check under this code for a result. I have changed the solenoid as I had a spare one. Checked the spark which is OK. I am stumped at the moment.