The P0598 code indicates that the engine control module has detected a voltage signal below the normal operating range in the thermostat heater control circuit. This typically occurs in vehicles with electronically controlled thermostats that use a heating element to regulate coolant flow.
The internal heating element within the electronic thermostat has failed, creating an open or short circuit.
Wires leading to the thermostat have been frayed, melted, or broken, resulting in a short to ground.
Corrosion or moisture at the thermostat electrical connector has increased resistance or interrupted the circuit.
A fuse dedicated to the thermostat heater circuit has blown, cutting power to the component.
An internal failure in the engine control module's driver circuit for the thermostat heater.
Not necessarily. A P0598 usually means the heater cannot force the thermostat open, which often results in the engine running too cold rather than too hot.
In many cases, yes, because the heating element is integrated into the thermostat assembly. However, you should verify the wiring first to ensure a new part isn't damaged by a short circuit.
Replacing the PCM is rarely the correct fix for this code. Almost all P0598 issues are caused by the thermostat itself or the wiring harness leading to it.