"Air Pockets" in coolant system signs.
 

For future reference:

"fault display coolant temperature possible to drive on"
"fault engine control possible to drive on"

Temperature readings disappear.

Not a classic case of the sticky thermostat but a cumulation of air pockets in the coolant system which turns into one big one which caused all the warnings.


For those who are curious on the super long wait times for engine to warm up (15mins) in the cold. Its normal, the coolant and cooling system in this car is really good.

Just a quick fyi from my service advisor.



The first picture is hard to see but the temp reading is missing.

Mike,that's interesting. I find it odd to have air pockets in a completely sealed system that builds up to 20 psi of pressure. Air pockets usually happen after a coolant flush or after something else has been serviced that required opening the coolant system. That's why a proper bleeding process is required afterwards.
Did he mention that he thinks it hasn't been properly bled at the factory?

Was yours a 2014? Engine replaced?

I don't own a 991GT3 :) ,but I know the proper operation of a coolant system. If air pockets appeared after engine replacement,then the coolant system hasn't been bled properly afterwards. If air pockets appeared on a car that came straight from the factory and didn't require an engine replacement,I can only assume it hasn't been properly bled at the factory...which I doubt.
Air pockets do not just develop for no reason,once the system is completely bled and sealed.

He did say that this was the first case and it was probably from in improper bled from the factory. You know your stuff man.


Milehigh, yes, 2014. Engine swap at port.

Thanks... There's our answer. Port engine swap and improper bleed of the system.

If it's a degas cooling system, then the system is self bleeding.
If it is not, then the fill port must be the highest point when re-filling the system, otherwise you get air trapped in the system.

i had the same issue engine swap at factory

I had an air pocket in my 997.2S after a radiator was replaced at a body shop. After the car warmed up I shut it off and let it cool for about a half hour. Removed the cap and topped it up. Did this twice and never had another issue.

Hi dude.... coincidentally my car started acting similar to what you are experiencing right after they replaced the radiator due to puncture. I started getting a blank reading from my coolant temp, similar to yours, and of course the coolant error message shows up then it would be Ok the next day. I also noticed the oil temp took a little longer to heat up. I took it back to the dealer and they thought it must be an air pocket trapped that is interfering with the reading of coolant temp, and Asked me to keep driving it and see if it goes away. For the next 2 weeks it continued to behave the same, with coolant temp, appearing and disappearing to eventually disappearing completely. Took it back to the dealer and this time they said it was the thermostat causing this issue after all, and it was replaced. Ever since they replaced the thermostat about a month ago and 1000 miles later, no trouble what So ever and problem is solved. I also noticed that my car oil temperature gets up to operating temperatures much much quicker and within 5 minutes of driving the car, even in very cold weather. Just keep an eye on yours, as it could still be the thermostat. Mark