My 04 astra 1.6 has been overheating have had my thermostat and temp sensor replaced but car is running at -40?

(2011-10-27 14:20:27) 1. Ruth Says: temp gauge does not move and fans do not start any body got a clue?? would appreciate any advice2. squealhole Says: -40 degrees is usually the preprogrammed lowest possible reading for both the outside temp sensor as well as the coolant temp sensor. It is in essence the value the computer gives when it sees an open circuit in the sensor. So is it saying the coolant is at -40 or the outside temperature? If it's the outside temp then you don't really have a problem, (except that you don't know how hot it is outside). If it's the coolant temp sensor then it still isn't a deal breaker. The thermostat works independent of the ECU and any sensors. It's mechanical and as such it won't let the engine overheat no matter what temp the ECU thinks it is at. The ECU though will make some odd decisions based on this information. If thinks that it is always -40 then it will always perform as if it's cold starting. So the cooling fans won't kick on, and it may add extra fuel into the cylinders or keep it on high idle. Basically it will do all it can to warm the car up, perpetually.
So long story short, it may hurt performance, mileage, and in the long run wear the engine a bit extra. The solution would be to identify the circuit for the sensor and using a voltmeter poke and prod until where you find where the circuit is open. Odds are it isn't the sensor it's a break in the wire somewhere.3. DR + Mrs Bears face Says: Hi so it probably needs something a bit more expensive by now the radiator for instance. or a new water pump and the only way would a visit to a vauxhall dealer for some diagnostics and not just poke and hope as seems to have been the case here.4. Junior Kwasi Says: the fan must be service to cool the radiator tank after the tank must be checked if it's leaking, if no check the holes inwhich the h2o go true if yes you service it or replays Tag: My 04 astra 1.6 has been overheating have had my thermostat and temp sensor replaced but car is running at -40?