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Cooling

P0128 Engine stays too cold (thermostat)

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P0128 means: Engine stays too cold (thermostat). The engine doesn't reach operating temperature in the expected time. OK to drive, but have it checked soon. The repair usually costs about €80–300 in Estonia. The most common cause: thermostat stuck open. Other possible causes: temperature sensor reads wrong, low coolant.

Is it safe to drive?OK to driveOK to drive, but have it checked soon.
Typical repair cost€80–300parts and labour in Estonia

What it means

The engine doesn't reach operating temperature in the expected time. Most often the thermostat is stuck open. It is almost always the thermostat. Fuel consumption goes up and the cabin won't get warm in winter.

What could be wrong

  1. 1Thermostat stuck open
  2. 2Temperature sensor reads wrong
  3. 3Low coolant

What you can check yourself

Watch whether the temperature gauge rises to its normal position (about 90 °C) while driving. In winter the cabin stays cold. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

  1. We monitor the temperature with a diagnostic tool
  2. We replace the thermostat, and the sensor if needed
  3. We top up and bleed the coolant

Standard SAE description: Coolant Thermostat (Temperature Below Regulating Temperature)

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong and what the repair costs before we start any work.

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Questions

What does fault code P0128 mean?

Engine stays too cold (thermostat). The engine doesn't reach operating temperature in the expected time. Most often the thermostat is stuck open. It is almost always the thermostat. Fuel consumption goes up and the cabin won't get warm in winter.

Can I drive with code P0128?

OK to drive, but have it checked soon.

How much does it cost to fix P0128?

Roughly €80–300 in Estonia. The price depends on exactly what has failed and on the car.

How is P0128 fixed?

We monitor the temperature with a diagnostic tool. We replace the thermostat, and the sensor if needed. We top up and bleed the coolant.

Related codes

P0116Engine temperature sensor reads wrongP0125Engine warms up too slowlyP0217Engine has overheatedP0480Fault in radiator fan control

This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.

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