Fault code P0597 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0597 – Thermostat Heater Control Circuit Open

P0597: Causes, signs and repairs

Error code P0597 is displayed and the check engine light is on - what does this mean?

DTC P0597 is triggered by the OBD/EOBD system when the thermostat heating control has a circuit fault. This trouble code affects the engine cooling system and the electronic thermostat control, which is responsible for the optimum engine temperature.

What causes can this fault code have?

Defective electronic thermostat
Damaged wiring to the thermostat heating element
Corroded or loose plug connections
Defective thermostat heating control
Short circuit in the heating circuit of the thermostat
Faulty motor control (ECM/PCM)
Broken earth cable
Overheated or burnt-out heating resistor

What symptoms occur in parallel with fault code P0597?

Extended warm-up phase: The engine takes significantly longer to reach operating temperature
Increased fuel consumption: Especially on short journeys and when the engine is cold
Poor heating performance: The interior heating does not get warm enough
Rough engine running: Especially during the warm-up phase when the engine is cold
Check engine light: Permanently illuminated check engine light
Reduced engine power: Noticeable when the engine is cold and the outside temperature is low

How can the problem with error code P0597 be rectified?

The repair requires a systematic diagnosis of the thermostat heating control.
Replacement of the electronic thermostat including the integrated heating element (approx. 150-300 euros material costs)
Repair or replacement of damaged cable connections between ECM and thermostat heater
Cleaning and renewal of corroded plug connections with contact spray and new seals
Replacement of the defective thermostat heater control in the engine control unit by a specialist company
Repairing short circuits by insulating damaged cable points and replacing cables
Checking and repairing the earth connections on the thermostat and engine block
Complete recalibration of the engine control unit after repair

FAQ - Frequently asked questions about DTC P0597

Can I continue driving with error code P0597?

In the short term, yes, but fault code P0597 should be rectified as soon as possible. The engine does not reach the optimum operating temperature, which leads to increased wear and fuel consumption.

How much does it cost to repair fault code P0597?

The repair costs for DTC P0597 are between 200-500 euros, depending on the vehicle model and whether only the thermostat or also cable connections need to be replaced.

How do I recognize a defective electronic thermostat with code P0597?

With error code P0597, the engine temperature remains low even after a long drive, the heating does not warm up and fuel consumption increases noticeably.

Can I repair fault code P0597 myself?

Simple plug connections can be checked yourself, but replacing the electronic thermostat with DTC P0597 usually requires specialist knowledge and special tools.

How long does it take to repair trouble code P0597?

Trouble code P0597 takes around 2-4 hours to rectify in the workshop, depending on the accessibility of the thermostat and the scope of the work required.

Does error code P0597 occur more frequently in certain weather conditions?

DTC P0597 is often detected in cold temperatures, as this is when the thermostat heater is under particular strain and defects become more apparent.

Vehicles in which fault code P0597 occurs most frequently

Error code P0597 is a manufacturer-specific EOBD code that mainly occurs in vehicles with electronically controlled thermostats and can occur particularly in modern diesel engines with complex temperature control, but is most common in the following vehicles:

BMW: 1 Series, 3 Series, 5 Series, X1, X3 (2008-2015)
Mercedes-Benz: C-Class, E-Class, GLK, Sprinter (2009-2016)
Audi: A3, A4, A6, Q3, Q5 (2008-2014)
Volkswagen: Golf, Passat, Tiguan, Touran (2008-2015)
Ford: Focus, Mondeo, Kuga, Transit (2010-2016)
Opel: Astra, Insignia, Zafira (2009-2015)
Peugeot: 308, 508, 3008, Partner (2010-2016)
Citroën: C4, C5, DS4, Berlingo (2010-2015)
Renault: Mégane, Laguna, Scénic (2009-2014)

If the code P0597 occurs in your vehicle, you should first check the plug connections on the thermostat and have the fault code read out using an OBD scanner. If the fault code occurs repeatedly, a professional diagnosis at a specialist workshop is recommended, as modern thermostat heating systems are complex and require a precise fault analysis.

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