P0598 — Thermostat Heater Control Circuit Low

What Does P0598 Mean?

P0598 is a diagnostic trouble code indicating: Thermostat Heater Control Circuit Low. This code relates to the vehicle speed and idle control system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of P0598

⚠️ Check Engine Light (MIL) illuminated
⚠️ Thermostat Heater reading at zero or minimum value
⚠️ Related system not functioning or in fail-safe mode
⚠️ Erratic idle speed

Common Causes

🔍 Open or broken wire in Thermostat Heater circuit
🔍 Poor ground connection at Thermostat Heater
🔍 Faulty Thermostat Heater with no output signal
🔍 Disconnected or loose Thermostat Heater connector
🔍 Blown fuse in related circuit

Frequently Asked Questions

What does P0598 mean?

P0598 indicates: Thermostat Heater Control Circuit Low. The vehicle's computer has detected that the Thermostat Heater is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P0598?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P0598 for extended periods may cause additional problems.

How much does it cost to fix P0598?

Repair costs for P0598 typically range from $20 to $300, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Repair broken wire or restore ground in Thermostat Heater circuit
🔧 Clean and secure Thermostat Heater connector and ground points
🔧 Replace failed Thermostat Heater

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

P0598: Thermostat Heater Control Circuit Low