P0597 on Audi
Thermostat Heater Control Circuit Open
P0597 on Audi vehicles indicates thermostat heater control circuit open. Au7o has documented this code across 4 Audi models — most commonly on A4, A7, Q5. 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 Audi range from $150 to $5,000, 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 Audi by Model
Audi A4(1 issue)
- Water Pump/Thermostat Failure2009-2020
The plastic water pump housing and thermostat are known failure points on Audi 2.0T engines. Leaks and failures typically occur between 60,000-100,000 miles. The plastic components crack from heat cycling.
Audi A7(1 issue)
- Thermostat Housing Coolant Leak2012-2018
The 3.0T V6 thermostat housing in the C7 A7 develops coolant leaks from the plastic housing and its O-ring seals. The housing is located at the front of the engine and cracks or warps over thermal cycling. Coolant leaks onto the serpentine belt area and can cause belt slippage or overheating if coolant loss is significant.
Audi Q5(1 issue)
- Coolant Leaks (Thermostat Housing and Hoses)2009-2017
Audi Q5 (2009-2017) experiences coolant leaks from thermostat housing, coolant flanges, and hoses. Plastic components crack with age/heat cycles, causing leaks. Symptoms include coolant smell, visible leaks under vehicle, low coolant warning, and overheating. If leaks ignored, engine overheats causing severe damage. Common leak points: thermostat housing, upper coolant flange, lower coolant flange, heater core hoses.
Audi Q7(1 issue)
- Water Pump and Thermostat Failure (Overheating)2007-2015
The 2007-2015 Audi Q7 (3.0T, 3.6L, TDI) experiences water pump and thermostat failures causing engine overheating. Plastic impeller water pumps fail from debris clogging or electronic failures. When pump fails, coolant flow drops causing rapid overheating and severe engine damage (warped cylinder heads, blown gaskets). Thermostat housings crack and leak coolant. Failure often occurs around 60k-80k miles. Preventive replacement recommended.
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View P0597 across all makes →Frequently Asked Questions
What does P0597 mean on Audi?▼
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 Audi specifically, this code is documented across 4 models.
What causes P0597 on Audi vehicles?▼
Common causes on Audi: 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 Audi?▼
Repair costs on Audi range from $150 to $5,000, depending on the specific model and root cause.
Which Audi models have P0597 documented?▼
Au7o has documented P0597 on 4 Audi models: A4, A7, Q5, Q7.