1 one 2 coolant temperature sensors? Loud fan!

[monz87]

Hello,

I have a 2004 Golf 1.6 automatic. The radiator fan suddenly started to sound like a plane engine and the engine management light was on. So I took it into the garage and an error code was up, they changed a coolant temperature sensor and apparently the problem went away. They did tell me that the car has 2 sensors but only one came up on the diagnostics. They said that sometimes the problem comes back and they have had to then change the 2nd sensor for other customers.

Anyway the same day coming back home the fan again became loud and when parked and engine switched off, the big radiator fan was constantly on and off like 30 secs on and 30 secs off and did that for ages! It sounded very loud as well.

I called the garage and they said to change the second sensor, the engine management light didn't come on though.

1. Does the car definitely have two coolant sensors and what the garage said is probably correct?
2. I read that it could be a fan control unit which has packed up and the whole radiator needs to be changed?
3. When the engine was off and I lifted the bonnet, only the large fan (passenger side) was coming on and off and the the small one wasn't. Does that mean something? How do I know if the small one even works?

Thanks

[Teflon]

I can't be certain about your particular engine but yes, there's more than once sensor, covering the fan, the engine ECU and the temperature gauge on the dash.

As for fan noise, well that's all subjective and without standing beside the car and hearing it it's impossible to comment. However, the motor is directly behind the radiator which gets some rain coming through in bad weather and if the car has done a lot of motorway miles with little need for the fan (like my son's Polo) then the motor can get partially or completely seized and that may be the noise you are noticing.

The obvious question is what does your temperature gauge say when all of this is going on?


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[monz87]

I can't be certain about your particular engine but yes, there's more than once sensor, covering the fan, the engine ECU and the temperature gauge on the dash.

As for fan noise, well that's all subjective and without standing beside the car and hearing it it's impossible to comment. However, the motor is directly behind the radiator which gets some rain coming through in bad weather and if the car has done a lot of motorway miles with little need for the fan (like my son's Polo) then the motor can get partially or completely seized and that may be the noise you are noticing.

The obvious question is what does your temperature gauge say when all of this is going on?


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The actual noise doesn't seem abnormal, just a fan spinning at high speed which in fact makes it really loud. But why its coming on at high speed constantly is the issue I guess...
The temperature gauge seems to be fine.