Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
If the coolant was leaking from the radiator area, than the radiator is the likely cause.
When you filled it up, it is probably not bled up and not full.
Look for a crack in the drivers side radiator tank.
Hope this helps.
The best way to bleed the cooling system is to use a coolant bleeding bucket.
You can make one from a plastic bottle with the bottom cut off the bottle.
The idea is to raise the coolant level to allow the air to burp out of the system.
You'll be surprised at how much more fluid it will take.
The ECM warning light is from a high coolant temperature condition.
I would take to engine covers off, and inspect everywhere else to see if it has any other slow leaks as well.
Also if the coolant overflow tank is way overfull, it will overflow and look like a leak.
The filler cap could be deteriorated and allowing the coolant to escape from the engine and overfilling the overflow tank.
If you take the filler cap off, you need to make a device that can allow you to fill the coolant to a higher level than normal.
So a powerade bottle etc could have a neck that fits with a little insulation tape to build up the thread.
You'll need to crimp the overflow hose so the fluid doesn't go into the overflow tank, until you're happy the system is bled.
The overflow tank has a dipstick, the full mark is the top triangle, the low mark is the low bottom triangle, the rest are circles.
Do not fill above the top triangle, continued filling overflows out of the tank which is normal.
Have seen many filler caps fail where they lose into the tank, the tank then loses because it too full, the engine cools down but doesn't pull the coolant back.
If you see steam from the radiator, it still may have a leak within the radiator.
I would replace the cap, if you have any doubt.
Ok, I'll wait to hear back from you after you get your new cap.
Did the system bleed up ok, and now runs without getting too hot?
Is the engine light now off?
It would have a DTC stored in the ECM from the overheat condition.
Yes, the cap on the engine.
It is the "radiator cap" as such, contains a pressure/vacuum valve valve assembly like a normal radiator cap.
Get a genuine cap from Holden, the aftermarket caps are not as good.