Thermostat Chevrolet Cruze 1.8 Z18XER (F18D4). How to replace and check

The life of the Opel Z18XER engine, as well as its copy of the F18D4, can not be considered a record, although its 250-300 thousand before overhaul, he pulls. The Chevrolet Cruze thermostat on F18D4 engines is one of the weaknesses of this engine. How to replace a thermostat, which is better to put to get rid of problems for a long time, is understood today.

Thermostat Chevrolet Cruze 1.8 F18D4. Where did the errors come from

The electronically controlled thermostat on 1.8-liter Chevrolet Cruze engines is equipped with a heater. Heating the antifreeze theoretically helps the engine to get to work faster, which affects both fuel economy and the life of the entire unit F18D4.

The electronic engine control unit supplies 12 V to the heater terminals and monitors the antifreeze temperature in real-time via a feedback circuit.

термостат круз
Design of the Chevrolet Cruze thermostat with electronic control: 1 – heating resistance; 2 – a plate of blocking of a big contour of circulation; 3 – thermostat heating connector; 4 – spring; 5 – small plate blocking the small circuit of circulation; 6 – thermostat with solid filler; 7 – pin.

Of course, if there are problems with the heater, the control unit immediately sends a signal to the driver in the form of error code 89, which is displayed on the on-board computer display on the instrument panel.

The issue is that the error 89 on the Chevrolet Cruze 1.8 requires clarification, as it is considered a service signal. Other faults may be hidden behind it, but if you connect a diagnostic scanner, the error is easy to locate.

ошибка 89

For example, any OBD II scanner can show clarifying and related error codes:

  • Р0597 — damage to the thermostat heater control circuit;
  • Р0598 — the voltage in the thermostat circuit is too low;
  • Р0599 — the voltage in the thermostat circuit is too high.

код ошибки

Thus in 80% of cases, judging by responses of owners of Chevrolet Cruze of 1.8 l, the reason for the affair of errors is not electric at all.

Problems with the Cruze 1.8 F18D4 (Z18XER) thermostat

The failure of the thermostat antifreeze heater on Z18XER engines is often dictated not so much by the unreliability of the heating element itself as by problems with the plastic housing and seals.

термостат круз
The plastic housings of Chevrolet Cruze thermostats do not differ in durability.

Constant leaks of antifreeze, both external and internal, break the tightness of the contact group of the heater. Due to the formation of sources of corrosion on the contacts are failures with the communication of the electrical part of the thermostat and the electronic control unit of the engine. Therefore, error 89 on the display.

The practice has shown that the internal seals of the heater itself, as well as the thermostat rod and the large valve plate, which is responsible for overlapping the antifreeze flow in a large circle, do not differ in durability. Sealants simply crumble after 5-7 years of operation.


The plastic case of the native thermostat of the Cruz 1.8 Z18XER engine (F18D4) also does not differ in durability. It is often the case that the body of the thermostat cracks after replacing the antifreeze and removing the airlock.


What can threaten the operation of the engine with a faulty thermostat:

  • overheating of the engine or prolonged overheating, depending on the position in which the thermostat valves are jammed;
  • high fuel consumption;
  • increased engine wear;
  • reduction of motor oil life;
  • inefficient operation of the heater and several other problems.

There is one more question about the standard Chevrolet Cruze 1.8 l thermostat. It is set to the mode of operation with a full opening of the big valve at a temperature of 105 °C. In some cases, this mode of operation of the engine may be too hot, so many owners are much more willing to switch to thermostats with a peak opening of the valve at a temperature of antifreeze 92 °C.

термостат на 105 градусов

From all this, we can conclude that the standard Chevrolet Cruze F18D4 thermostat in case of issues with it, as well as the appearance of error 89 (P0597-P0599), is better to replace rather than restore the old one.

Which is better to replace the Chevrolet Cruze thermostat

We will start from the fact that the original GM 96984104 thermostat (25199829, 25193683, 55597008) costs about $ 55-60. Too expensive.

термостат круз

Moreover, among the analogs, even with a built-in heater, there are no less worthy options:

  • BEHR (MALHE) TM41105, this is the original thermostat, but without the GM brand label;
  • GATES TH445105G1;
  • KRAFT KT019524;
  • STELLOX 2340046SX;
  • Luzar LT0505;
  • Pierburg 704879000;
  • WAHLER 4431105D;
  • NSP NSP0155597008.

The price of these thermostats is from $30 to $70, depending on the brand. We do not recommend buying a Chevrolet Cruze used thermostat, as its condition is completely unknown, although it can be three times cheaper.

термостат круз
The original thermostat from GM (right) is also released by the Behr brand.

Thermostat Chevrolet Cruze 1.8 F18D4 without heater

To remove the heater, sometimes install a thermostat in a metal housing without it. Stops at GM 24 435 102 from Opel Insignia.

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Original Opel thermostat GM 24 435 102

Its price is not much less than the original heated thermostat, so it makes sense to look for analogs at 92 degrees from the Opel model range. Example:

  • Febi 39145;
  • Swag 40939145;
  • OTO Akdeniz 96984103;
  • Blue Print ADG09256.
термостат круз
Thermostat without heater by Borg Warner

If we decide to install a thermostat with a heater at 92 degrees or a thermostat without it, it is necessary to correct the firmware of the electronic engine control unit. At a minimum, to change the modes of operation of the radiator cooling fan.

In normal mode with a standard thermostat, the fan turns on:

  • first speed — 108 °С;
  • 2-d speed — 116 °С;
  • 3-d speed — 119-120 °С.

In order not to change the thermal regime of the engine, the firmware must specify the following values:

  • 1 speed — 98 °С;
  • 2 speed — 105 °С;
  • 3 speed — 112 °С.

If we put the case of the thermostat Chevrolet Cruze 1.8 without a heating element, it is also necessary to make some improvements, if it is not possible to flash the engine control unit. Otherwise, the ECU, without detecting the heater, will constantly knock out error 89.

Denominations of standard resistances, which are in every radio shop.

To convince the control unit that the heater is, it is enough to hang a resistance on the contact pad, which gives the heating element. It is necessary to buy a resistor with a power of 5 W with a value of 30-32 Ohms. Alternatively, you can connect two powerful resistors of 60-65 Ohms in parallel.

Resistance soldered in parallel.

After that, the terminal block must be hermetically sealed. For this purpose, the finger from a latex medical glove will quite approach.

One of the options for sealing the thermostat heating connector.

After this processing, error 89 (P0597-P0599) will no longer bother you. It remains to decide on the option of the thermostat and start the replacement.

How to replace the Chevrolet Cruze 1.8 F18D4 thermostat

Depending on the condition of the antifreeze, it is not necessary to drain it completely for replacement. However, keep in mind that when dismantling, the thermostat will spill up to a liter of coolant.

Therefore, you need to think about where to place the capacity of the required volume, so as not to contaminate the engine and the floor in the garage. And it is better to drain a couple of liters of antifreeze from the drain fitting in the lower-left corner of the cooling radiator. The replacement process is generally similar to replacing a thermostat with an Aveo T300.


The procedure for replacement is as follows:


  1. Unscrew the screws on the right, remove the clips on the left and remove the protection.
  2. Drain the antifreeze from the drain cock.
  3. We get access to the thermostat.
  1. Slide the clamp further along the hose.
  2. Disconnect the heater contact pad.
  3. Remove the receiving pipe


  1. Unscrew the 4 bolts around the perimeter.
  2. … head E10
  3. When tightening, adhere to a force of 8 Nm.


  1. After assembly, pour (top up) antifreeze…
  2. …expel the air lock
  3. Heat up and check the pipes for leaks.

Thus, you can solve the problem with the Chevrolet Cruze thermostat on the Z18XER engine (F18D4).

One thought on “Thermostat Chevrolet Cruze 1.8 Z18XER (F18D4). How to replace and check

  1. Hi,
    Many thanks for the usefull information. I installed the 92C thermostat and the resistor and everything works just fine. Regretfully I am not able to update the firmware on ECU, nor does my Tech2 professional, so the radiator fan continue to kicks in at 108C. I would like the fan to start at 98C but that’s not possible since it is an ECU cotrolled and there no thermo switch which I can replace. Is it possible to use a resistor somewhere in the termostat housing sensor wiring or elsewhere so I could get the radiator fan to start at lower temp? This is importatnt for city driving, since at the highway the temp of 92C is constant.

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