P0598 on Buick
Thermostat Heater Control Circuit Low
P0598 on Buick vehicles indicates thermostat heater control circuit low. Au7o has documented this code across 1 Buick model — most commonly on Encore GX. This code applies to engines with an electronically controlled (heated) thermostat and means the Powertrain Control Module detected an abnormally low voltage in the thermostat heater control circuit. The heater element lets the computer fine-tune coolant temperature for efficiency and emissions by opening the thermostat sooner under certain conditions. P0598 sets when the control or feedback circuit reads lower than expected (often a short to ground or loss of supply). It is found mainly on certain European makes (BMW, Mercedes, VW/Audi, etc.) and usually has little effect on driving. Typical repair costs on Buick range from $600 to $1,500, depending on the specific model and root cause.
Common Causes of P0598
- •Faulty electronically controlled (map-controlled) thermostat
- •Short to ground in the heater control wiring
- •Corroded or loose thermostat connector
- •Open or damaged wiring in the control circuit
- •Low coolant level overheating the thermostat heater
- •Blown fuse or poor power supply to the circuit
- •Faulty PCM control driver
P0598 on Buick by Model
Buick Encore GX(1 issue)
- Plastic Coolant Control Valve / Water Pump Assembly Failure Causing Overheating (P3075)2020-2024
The three-cylinder turbo cooling system uses an electrically actuated multi-port coolant control valve with a plastic housing and rotor that directs flow between the block, heater core, turbo and radiator circuits. The plastic rotor binds or the housing cracks, and the integrated water pump module can fail alongside it. Because the ECM cannot achieve commanded coolant flow, it sets a coolant-flow-low fault and the engine overheats, typically after 20-25 minutes of continuous driving. Owners describe an erratic temperature gauge that swings before the overheat warning appears. Because the valve sits in a tight three-cylinder bay, labor is a large share of the bill.
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View P0598 across all makes →Frequently Asked Questions
What does P0598 mean on Buick?▼
P0598 stands for "Thermostat Heater Control Circuit Low." This code applies to engines with an electronically controlled (heated) thermostat and means the Powertrain Control Module detected an abnormally low voltage in the thermostat heater control circuit. The heater element lets the computer fine-tune coolant temperature for efficiency and emissions by opening the thermostat sooner under certain conditions. P0598 sets when the control or feedback circuit reads lower than expected (often a short to ground or loss of supply). It is found mainly on certain European makes (BMW, Mercedes, VW/Audi, etc.) and usually has little effect on driving. On Buick specifically, this code is documented across 1 model.
What causes P0598 on Buick vehicles?▼
Common causes on Buick: Faulty electronically controlled (map-controlled) thermostat, Short to ground in the heater control wiring, Corroded or loose thermostat connector, Open or damaged wiring in the control circuit, Low coolant level overheating the thermostat heater. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0598 on a Buick?▼
Repair costs on Buick range from $600 to $1,500, depending on the specific model and root cause.
Which Buick models have P0598 documented?▼
Au7o has documented P0598 on 1 Buick model: Encore GX.