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Known fault

M270: a failing electric thermostat leaves the engine cold

Typically above 90,000 km. It does not show up on every car.

expensive

severity

above 90,000 km

mileage

2

sources

2 sources next to the write-up.

The fault

How you spot it

The electric thermostat can fail from 90 000 kilometres and sticks open. The coolant then circulates in the large circuit even while the engine should still be warming up, so the engine does not reach its 80 degree operating temperature.

The control unit logs it too: code P0128 means that the coolant temperature stays below the regulating temperature of the thermostat. The symptom is that the engine does not warm up properly even after a long time, the heater is lukewarm, consumption rises and the engine management light comes on as well.

An engine running cold for a long time wears faster, because cold oil does not lubricate the same way and fuel dilutes it in a greater proportion. The thermostat is built into the coolant circuit, so its replacement involves draining coolant.

Which model

Who it affects

The card opens the generation, the engine or the transmission.

Engines and transmissions

Checklist

M270: a failing electric thermostat leaves the engine cold

What you would check for this fault. Take it to the car.

Before you buy

Checklist

What you tick stays on this device only.

vinkodex.com · Before you buy it, see what can go wrong.

Sources

How we know

Information, not an expert opinion

We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.

  • A fault on the list does not mean the car you are looking at has it.
  • A fault missing from the list does not mean the model is fault-free. Write-ups are made model by model. Not all of them are done.
  • You decide whether to buy. This is no substitute for an inspection. That needs a workshop and a history check.
Details in the terms