P0597 on Mercedes-Benz
Thermostat Heater Control Circuit Open
P0597 on Mercedes-Benz vehicles indicates thermostat heater control circuit open. Au7o has documented this code across 1 Mercedes-Benz model — most commonly on A-Class. P0597 is a cooling-system code indicating an open electrical circuit in the control for the heated (electronically controlled) engine thermostat. Many modern engines use a thermostat with a built-in heater element that the computer can energize to open the thermostat sooner for better temperature management and emissions. When the PCM commands that heater but detects no electrical continuity (an open circuit), it sets this code. It generally means the thermostat heater isn't being controlled, which can affect coolant temperature regulation, fuel economy, and emissions. Typical repair costs on Mercedes-Benz range from $350 to $900, depending on the specific model and root cause.
Common Causes of P0597
- •Failed thermostat heater element or integrated control thermostat
- •Open or broken wiring to the thermostat heater circuit
- •Corroded, loose, or disconnected thermostat connector
- •Blown fuse or open in the heater power feed
- •Poor ground or control-circuit fault from the PCM
- •Damaged PCM driver for the heater (rare)
P0597 on Mercedes-Benz by Model
Mercedes-Benz A-Class(1 issue)
- M282 Thermostat Housing / Coolant Leak2019-2023
The 1.3L M282 engine develops coolant leaks at the integrated thermostat housing/gasket and at the water pump and coolant hoses, commonly in the 55,000-70,000 mile range. A failing thermostat housing causes temperature gauge fluctuation, coolant loss, and slow cabin heating; if ignored it can lead to overheating. Coolant leaks are repeatedly cited as one of the most common cooling-system issues on A 250/A 200 owners.
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View P0597 across all makes →Frequently Asked Questions
What does P0597 mean on Mercedes-Benz?▼
P0597 stands for "Thermostat Heater Control Circuit Open." P0597 is a cooling-system code indicating an open electrical circuit in the control for the heated (electronically controlled) engine thermostat. Many modern engines use a thermostat with a built-in heater element that the computer can energize to open the thermostat sooner for better temperature management and emissions. When the PCM commands that heater but detects no electrical continuity (an open circuit), it sets this code. It generally means the thermostat heater isn't being controlled, which can affect coolant temperature regulation, fuel economy, and emissions. On Mercedes-Benz specifically, this code is documented across 1 model.
What causes P0597 on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: Failed thermostat heater element or integrated control thermostat, Open or broken wiring to the thermostat heater circuit, Corroded, loose, or disconnected thermostat connector, Blown fuse or open in the heater power feed, Poor ground or control-circuit fault from the PCM. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0597 on a Mercedes-Benz?▼
Repair costs on Mercedes-Benz range from $350 to $900, depending on the specific model and root cause.
Which Mercedes-Benz models have P0597 documented?▼
Au7o has documented P0597 on 1 Mercedes-Benz model: A-Class.