SureTrack Real Fix: Thermostat Heater Control

Real Fixes from the SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is currently available free with the purchase of a current Snap-on® diagnostic software version.

Engine coolant thermostats used to be pretty simple devices. But as with everything else automotive, they now have electronic controls. Follow this Real Fix to see how a 2015 Opel/Vauxhall with a code P0597 for the thermostat heater control circuit was diagnosed and the component that caused the problem.

Vehicle
2015 Opel/Vauxhall Mokka 1.6 Petrol

Title
P0597, Replaced Engine Coolant Thermostat Housing

Complaint
The customer states the check engine light is on.

Cause
Connected a scan tool and found code P0597 – Thermostat Heater Control Circuit/Open. With the scan tool connected, monitored live data and found the engine coolant temperature was within the specified operating temperature. Used a multi-meter to backprobe the thermostat heater control electrical connector and found voltage and ground were present. Disconnected the connector from the thermostat heater control, inspected the connector, terminals and wiring harness and found no faults. Measured the resistance of the thermostat heater control and found no continuity. These test results verified the thermostat heater control was faulty. The thermostat heater control is integrated into the engine coolant thermostat housing and is replaced as an entire unit.

Correction
Replaced the engine coolant thermostat housing, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.


SureTrack® is a powerful value-added feature available with select Snap-on diagnostics tools. It offers an exclusive combination of expert knowledge and detailed parts replacement records, all wrapped in an interactive community.

Want more? Click here for more information on using SureTrack.

New or Expired SureTrack users: Click here for authorization key instructions.

About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.