P0599Medium urgency
Thermostat Heater Control Circuit High
Engine · Cooling System
⚠️ Thermostat heater control impaired. Service within 1–2 weeks.
What this means
The electronically controlled thermostat heater circuit signal is reading high — typically from a short to voltage.
Likely causes
- Heater circuit short to voltageMost common
- Failed thermostatMost common
Estimated repair cost
Electronic thermostat$80 – $300
Wiring repair$80 – $200
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Frequently asked questions about P0599
What does P0599 mean?
The electronically controlled thermostat heater circuit signal is reading high — typically from a short to voltage.
Is P0599 serious?
Thermostat heater control impaired. Service within 1–2 weeks.
How much does it cost to fix P0599?
Repair costs for P0599 range from $80 – $300 depending on the root cause and your vehicle.
Can I drive with P0599?
You can drive short distances but should have it repaired within 1–2 weeks to prevent further damage.