C250 2009 radiator fan running full speed!

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Mar 6, 2025 | 10:23 AM

TruongNguyen

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Joined: Aug 2022

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C250 W204

C250 2009 radiator fan running full speed!

Hello everyone!
Today, I started my car after 2 days of not running it, and I noticed that the engine cooling fan was making a very loud noise and spinning at maximum speed, even though the engine temperature was in a cold start state. The engine temperature gauge was showing around 20°C. Can anyone help me figure out the cause of this issue?

Below is an image of the fault code I scanned
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Mar 7, 2025 | 11:58 PM

TimC300

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Joined: Aug 2023

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From: MA Coast

W204 2010 C300 4matic Sport M272

I dont have that engine so not sure what the codes mean.

For some reason I thought if the fan is running on high it may mean the coolant temp sensor is faulty, the fan runs on high by default.

Mar 9, 2025 | 01:06 AM

bazzbazz

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Joined: Sep 2024

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C200 w204

I agree with TimC300, the usual cause of the radiator fans stuck on is a faulty Coolant Temperature Sensor.

As for the scanned fault codes you need to clear them all and see which ones, if any, return.