I have a Vauxhall meriva B 2012 1.4 petrol been all ok till a code 4 and engine light came on ive replaced manual thermostat, water pump,expansion bottle and still no luck I am replacing the electric thermostat today but any other advice welcome, have flushed and refilled and bled the system so dont think i have any more air in there so am now a bit stumped also the R10 gets really hot the minute I turn the car on any help appreciated..