My car is throwing a P0599 code. I reset it once and it took about 2 weeks for it to come back. I have heard about the thermostat housing being a problem with some cars. Could that be the culprit here? Does it even affect the N18? Build date is 3/2011 if it matters.

For the record my SGII shows 210F-225F coolant temp on average just as it always has.

 

Bump...anyone have any input on this issue?

 

I have the same issue now and same symptoms. The car is not overheating and the heater works fine, right at 215-225 degrees and a persistent CEL. Mine is a 2/11 build 2011S that has had the thermostat and both water pumps replaced under warranty once already.

Sean

 

I ended up replacing the thermostat (again) and it has not come up again.

Sean