2011 Cayenne V6 MT - faulty thermostat?

[Charles Andersen]

Hello,

 

I have a 2011 Porsche Cayenne V6 mt.

 

It has a check engine light on now, and when I turn it on on a cold day (i.e. 30 degrees F) the engine coolant will warm up from <30 to perhaps 120 degrees F in maybe 10 minutes at idle/with car stationary.  Then, as I drive, the coolant temperature will fall, especially if on the highway (higher speeds / lower revs).  Occasionally, I will get a temperature sensor error (at which point dial swings to 260+F and the dial blinks), but it seems to happen only when the coolant temperature will fall below a certain point.

 

Does this sound like a faulty temperature sensor?  Or a thermostat that is stuck open perhaps?  Car is running with marginally worse fuel economy also.

Edited December 10, 2018 by Charles Andersen
added information

[Loren]

 

Fault codes... fault codes... fault codes. Everything becomes an expensive guess without the fault codes.

If you do not have a scan tool then find an auto parts store that will check your fault codes for you. Write them down and report them back here. Then we can hopefully point you in the right direction.

[Charles Andersen]

Current codes (some listed twice because they appear twice):

1. P0441 - Evaporative Emission System Incorrect Purge Flow

2. P0456 - Evaporative Emission System Leak Detected (very small leak)

3. P017B -

4. P2181 - Cooling System Performance

5. P0441 - Evaporative Emission System Incorrect Purge Flow

6. P0456 - Evaporative Emission System Leak Detected (very small leak) 

7. P2181 - Cooling System Performance

 

Does this sound like a bunch of smaller things, or a more major thing?

[Loren]

I suggest you clear them all - then drive the car and re-check the faults.

[Charles Andersen]

turned out to be thermostat.  Replaced and fine now.turned out to be thermostat.  Replaced and fine now.