I have got Astra H, Z16XEP engine.

The engine operates in very high temperatures originally - 105-113°C.

I want to lower a bit temperature the radiator fan kicks in: currently 113°.

How that could be done? Maybe reprogramming / programming? Opcom, Tech 2? Or replacement of some of car's modules?

  • 2
    Why do you want to do this?
    – Caius Jard
    Commented Oct 13, 2021 at 20:16
  • 1
    There's a good reason the fan kicks in at that temperature, I'd think twice before changing it, then I'd think about it longer and not do it.
    – GdD
    Commented Oct 14, 2021 at 13:00
  • @CaiusJard I had a coolant radiator exploded once. I had a hose exploded too. Other Opel engines, produced similar years operate much colder. Some later engine models operate colder too.
    – JRr
    Commented Oct 14, 2021 at 18:15
  • @GdD There are Opel / Vauxhall engines from same generation running much colder. At first glance, work range is 105°-113°. But at high load ECU opens thermostat at 90° and at highway Z16XEP operates at that temperature. At short distances and in colder climate 105°-113° is not reached/reached slower. I had my cooling system exploded two times and engine barely survived and I desperately want my temperature lower.
    – JRr
    Commented Oct 14, 2021 at 18:28

1 Answer 1


Most fans have a switch fitted in the cooling system - change that for one of a lower temperature rating. They are often the same size.

However, you could do what I did and fit a tank thermostat around one of the radiator hoses then adjust it until it comes on at the temperature desired. Trial and error here as the ambient temperature under the bonnet varies so you have to experiment.

  • Where is located that switch / electronic module for Z16XEP engine? Or what is its name?
    – JRr
    Commented Oct 15, 2021 at 10:53

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