Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the part of the car that helps control the engine's temperature. It's like a heater isn't working right to keep the engine warm.
The P0598 code indicates that the engine control module (ECM) has detected a low voltage in the thermostat heater control circuit.
The thermostat heater control circuit is responsible for regulating the engine's temperature by using a heater element to open or close the thermostat. A low circuit condition means the voltage is below the expected level, which can affect engine temperature regulation.
• Check Engine Light is on
• Engine overheating
• Poor fuel economy
• Temperature gauge reading unusually
• Faulty thermostat heater
• Open or shorted thermostat heater circuit
• Poor electrical connection in the thermostat heater circuit
• Faulty ECM
ECM: Engine Control Module
OBD-II: On-Board Diagnostics, second generation
• Use an OBD-II scanner to confirm the code.
• Inspect the thermostat heater and its wiring for damage.
• Check for any loose or corroded electrical connections.
• Test the thermostat heater for proper resistance.
• Repair or replace damaged wiring or connectors.
• Replace the thermostat heater if faulty.
• Repair or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $300
Moderate
• Chevrolet Cruze
• Ford Focus
• Volkswagen Jetta
• Regular maintenance checks on the cooling system.
• Ensure proper electrical connections.
• Replace thermostat at recommended intervals.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
• Monitor engine temperature gauge regularly.
Check with the vehicle manufacturer for specific warranty coverage on emissions-related components.
This code has been commonly reported in vehicles with electronic thermostat controls, especially in models from the late 2000s onwards.
Moderate – While the vehicle may still be drivable, it can lead to engine overheating if not addressed.
Driving with this code may lead to engine damage and is not recommended. Always follow safety guidelines when performing repairs.
• Engine at operating temperature
• Ignition on, engine off
The thermostat heater is typically located near the engine block, integrated with the thermostat housing.
Q: Can I drive with a P0598 code?
A: It's not recommended to drive for long periods, as it may lead to engine overheating.
Q: How can I reset the P0598 code?
A: After repairs, use an OBD-II scanner to clear the code. If the issue is fixed, it should not return.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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Fitment Required · Vehicle-fitment part
Relevant when coolant-temperature and warm-up faults indicate a thermostat-related issue.
Coolant-temperature and warm-up faults often lead to thermostat testing and replacement.
Thermostats are vehicle-specific and should be matched by engine and housing style.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.