Coolant Warning Light

[yg54sg]

I needed to hook the car up to clear airbag fault, while i was there I checked for error codes , seems I have error code P0599 which is Thermostat heater control high, I think this related to the thermostat itself? The most recent error was the last journey, all the temps look within specification (in the greem) upon checking the info > analogue ODB2 data.

Im guessing I should change the thermostat even though there is nothing wrong in terms of no overheating and the car gets up to temp within 20 mins so dont think its stuck.... Im guessing these BMW thermostats have a temp sensor and other stuff in them.... not just a simple metallic strip?


P0599 - Thermostat Heater Control Circuit High

Possible causes
- Open or short thermostat heather control circuit
- Poor thermostat heather control circuit connection
- Failed Engine Cooling Thermostat

Tech notes
If there are not coolant system leaks, replaced the thermostat to fix the problem.

When is the code detected?
The P0598 is triggered when there is an open or short thermostat heather control circuit.

 

[bcworkz]

...seems I have error code P0599 which is Thermostat heater control high, I think this related to the thermostat itself? The most recent error was the last journey, all the temps look within specification (in the greem) upon checking the info > analogue ODB2 data.

Im guessing I should change the thermostat even though there is nothing wrong in terms of no overheating and the car gets up to temp within 20 mins so dont think its stuck.... Im guessing these BMW thermostats have a temp sensor and other stuff in them.... not just a simple metallic strip?

A problem with the heater circuit will not manifest itself except under very high engine load conditions. I would first clear the error, then check again later to see if it returned. If it did not trigger the CEL, it's not anything urgent to address. The thermostat is more than a bi-metal controlled valve, but not much. No sensors are involved. The wiring is for the heater circuit. The ECU can heat a wax capsule on demand to cause the thermostat to act as a lower rated one. That's the extent of it.

 

[yg54sg]

thanks bc will clear it and monitor over the next few months