I have a 07 Corsa club auto that when you drive it the coolant goes down fast. I have taken it to a mechanic and what they have done was "Removed part of wiring loom from engine to be able to replace 1 wire from ecu to oil pressure switch and also replaced oil pressure switch as that was the main fault as oil travalled through the sensor and wiring all the way to the ecu. Sent ecu off for testing and after cleaning out all the oil found that the ecu wasn't faulty, re fitted ecu and then run up to temperature and a long road test cooling fan now cuts in and cools engine as normal". The problem is still there and don't know what to do. Do I take it to a different mechanic? Is this a known problem?