Eric Busto

Has anyone else had an issue where their car was having trouble getting up to operating temperature, even after having the thermostat replaced? The coolant temperature will briefly hit 194, then drop down to the mid 170s. The oil temperature struggles to hit 180, and will usually steady state at around the same temperature as the coolant.

All codes were cleared after the thermostat was replaced, but the behavior persists and the code is back.

asellus

I assume it's out of warranty and yeeting it to the dealer isn't an option here...

Failure to maintain temperature is a function of the thermostat, yes, however the 991's cooling system is profoundly complex. It may be worth looking into the COV issues these cars are known for, as I believe some of those control coolant flow.

Jack F

Well stated….profoundly complex.

Fullyield

As others indicate, the COV for your thermostat has most likely failed. To prevent damage to your engine from overheating, it should fail to the fully open position which explains your below normal temps.

Eric Busto

The car is still under the CPO warranty. I was mostly trying to determine if this will be a quick fix, or if the service department will have a tricky time diagnosing and fixing it.

I've read plenty of threads on 991.1s having COV issues, so I'm a bit surprised that it would be an issue on my 991.2, but looking at the cooling system diagram, that does seem like the next logical component that could be causing the problem.

asellus

Oh, it's CPO? Just throw it at the dealer and be done with it. They'll take 1-3 days to diagnose it, another week to fix it, and you'll have a Macan or Cayenne or something in the meantime.

Eric Busto

It is a three hour round trip drive to the nearest dealer, so it isn't quite that simple. If it is a quick fix, I would try to drive it down early in the morning and then wait while it is repaired. If it isn't a quick fix, I need to either work out a day when they'll have a loaner available (in my experience with this dealer, they run out of loaners pretty easily), or have it towed and then catch a ride down when it is fixed. Uber and Lyft aren't really options in my area.

asellus

Ah, that's a major bummer.

Hate to tell 'ya, if it's a COV problem it's not a simple/quick fix, as a number of those valves are buried in the engine bay. Then there's the need to order parts in the likely event they don't have them on hand, which is going to be overnight at minimum.