OBD-II code · Powertrain (generic)
P0597 Thermostat Heater Control Circuit Open
The map-controlled thermostat - electrically heated to lower its opening temperature on demand for emissions or torque mapping - has an open control circuit. The ECU loses the ability to override coolant flow timing.
Is it safe to drive with P0597?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen in heater element or harness
- Less likelyPin pushed back out of connector body
- Less likelyCracked solder joint inside the module or sensor
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- Parts involved
- Map Thermostat Heater
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.