The P0598: Thermostat Heater Control Circuit Low refers to a problem where the thermostat heater control circuit is detecting a low voltage. This could be caused by a faulty control circuit, low voltage, or wiring issues, potentially affecting the engine’s ability to regulate temperature efficiently.
P0598 – Quick Overview
Code | Information |
---|---|
Meaning | P0598: Thermostat Heater Control Circuit Low |
Is it serious? | Yes, as it can lead to inefficient engine temperature regulation, affecting performance. |
Possible causes | – Faulty thermostat heater control circuit – Low voltage in circuit – Wiring issue |
How to diagnose? | – Test thermostat heater control circuit for voltage – Inspect wiring and connectors – Test thermostat heater |
P0598 Meaning
The P0598 code indicates that the thermostat heater control circuit is experiencing lower-than-expected voltage. This may result from a faulty thermostat heater control circuit, low voltage supply, or issues with the wiring. If left unaddressed, it can cause the engine temperature to become improperly regulated, affecting performance and efficiency.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for other related codes that could assist with diagnosis. | OBD-II Scanner |
Test the Thermostat Heater Control Circuit | Use a multimeter to measure the voltage in the thermostat heater control circuit and ensure it is within specification. | Multimeter |
Inspect Wiring and Connectors | Inspect the wiring and connectors for damage, disconnections, or corrosion that could cause low voltage. | Flashlight, Multimeter |
Test the Thermostat Heater | Verify that the thermostat heater is functioning properly and maintaining the correct temperature control. | Diagnostic Tool, Multimeter |
Clear the Code and Test | After repairs, clear the code with an OBD-II scanner and test the vehicle to confirm the issue is resolved. | OBD-II Scanner, Vehicle Manual |

Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)