Does your car still have a sump cover on it under the engine to protect it from bumps. If yes then I can't help but if it doesn't, get on the floor n have a look underneath. The sump has a lead connected to it underneath and if you have driven over some long grass it could of simply pulled the lead out. I did this in my 02 golf and it just kept saying STOP check oil. After checking oil and it being ok I parked with 2 drivers side wheels on the car n spotted the lead plugged it back in n it was fine. Good luck let me know if it was any use to you thanks
Rigby 02 we shall fly!, July 2016