Blue Print solves Chevrolet and Vauxhall thermostat heater control system fault

Common problems causes cooling fan to constantly run, poor heater performance or engine overheating

Blue Print solves Chevrolet and Vauxhall thermostat heater control system fault

Blue Print offers practical support with everyday issues encountered in the workshop and, when possible, follow the explanation structure of problem, cause, solution.

Here we discuss a problem which can arise on certain Chevrolet and Vauxhall models which can be solved using Blue Print Thermostat ADG09255.


The engine cooling fan is constantly running, poor heater performance or the engine is overheating.

The engine warning lamp is illuminated, related to the symptoms listed above.

These possible fault codes may be stored in the engine ECU:

  • P0597 – Thermostat heater control system – open circuit.
  • P0598 – Thermostat heater control system – circuit low.
  • P0599 – Thermostat heater control system – circuit high.


An old, or incorrect, type of coolant is being used – causing corrosion or sludge buildup in the cooling system, preventing the thermostat to fully close or open.

If the coolant temperature is detected to be above or below the optimum temperature range, the engine control unit has a built-in failsafe mode that will switch on the cooling fan.


Before replacing the thermostat, inspect the electrical connection and check the water temperature sensor is operating correctly.

Once the thermostat has been identified as the source of the issue, flush out the coolant system and replace the thermostat.

Replace the manufacturer’s recommended coolant, bleed the cooling system of any air and clear the fault codes using a suitable diagnostic tool.

Blue Print’s thermostat ADG09255 fits Chevrolet Cruze (J3), Aveo (T3), Vauxhall Adam (M13), Astra J, Corsa D, Corsa E, Meriva B with engines: LDC, LDD, LWD, A12XEL, A12XER, B12XEL, Z12XEP, A14XEL, A14XER, B14XEJ, B14XEL, B14XER, Z14XEP.

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