[Gibbo]

Possible causes of OBD code P0599
- Open or short thermostat heather control circuit - Poor thermostat heather control circuit connection - Failed Engine Cooling Thermostat The Error code is generally activated on detection of the following conditions: The P0598 is triggered when there is an open or short thermostat heather control circuit.

Peugeot P0599 OBD/DLC Error Code - Thermostat Heater Control Circuit High

I'm guessing you didn't get this code from Peugeot Planet or Diagbox. If you did you could get parameter measurements.

 

[Gibbo]

Yep, someone else on here had a similar problem and tried a new housing and that sorted it.

 

[Gibbo]

Check everything is plugged back in. It wouldn't be the first time a mechanic left something disconnected when reassembling.