P0597 - Thermostat Heater Control Circuit/Open

The thermostat heater control circuit is open.

Code Overview

The thermostat heater control circuit is open.

Common Causes

• Thermostat heater or assembly fault
• Damaged wiring or connector
• Control circuit issue

Diagnostic Steps

1. Inspect thermostat heater connector and harness
2. Check command and voltage at the heater circuit
3. Confirm cooling-system operation before replacing parts

Likely Repairs & Cost Guides

Use test results to confirm the fault before pricing the repair.

Related OBD Codes

Browse the closest code-family pages when the same fault pattern often shows up nearby.

Next Steps

Move from the code to a diagnosis path, then into repair pricing once the fault is confirmed.