Engine fan turns on all the time, even when it's cold

[Satsumomo]

Hi everyone!

Car: 2014 Leon FR 1.4 with 55,000 km, no mods.

This has been happening for at least a month now, and before I take it to the dealership, I would like to know if maybe this is an easy fix that someone here knows about.

Very often, in the morning, it's 18ºC outside and yet when I turn on my car, about a minute or two while idling in my driveway, the fan will turn on. And it will not turn off until I reach my destination.

Water temperatrue never goes above the 90ºC mark, and my oil temperature hovers around 93ºC-95ºC.

Funnily enough, when it's hot outside (31ºC+) then fan seems to function normally, as in it doesn't turn on immediately, but if it does, same story, it doesn't turn off again.

This really bothers me since it tells me that a sensor must be wrong, but it also prevents the start/stop system from working. Any idea what it could be?

 

[BoomerBoom]

Is the aircon on? To my knowledge the fan will run continuously when it's switched on.

Try turning the aircon off and see if the fan stops.

 

[Satsumomo]

Nope, I very rarely use it.

I also live at 1,500m above sea level if that means anything.

 

[cupra14]

I'd check whether it thinks (wrongly, perhaps) that the engine/coolant temp is hotter than it actually is so is trying to cool it.

So, maybe a failed temp sensor.

 

[SRGTD]

I had a mk4 Golf back in 2003 that did this. Turned out to be a failed temp sensor which was replaced and the problem was cured.

 

[Satsumomo]

Any idea on where the sensor is? I downloaded the service manual but so far I haven't found it.

 

[Satsumomo]

Hey everyone, still trying to figure this one out...

 

[LouG]

This help?

 

[Satsumomo]

Thank you, I'll check it out today.

 

[Satsumomo]

So a follow up, I finally solved the issue.

It was the car battery!

First off, I bought this car used, but it's in really good shape, 2014 model with about 45,000 km and it looks almost brande new. Mechanically very sound and no issues. Save for one that had been getting worse and worse: The darn fan turning on all the time.

One of the "symptoms" was that the start-stop system would not work, and I always assumed it was because of the fan. But I also started to think "Maybe I should get a deep cycle battery, that would help with the start-stop system" so I start to do some research and I learned about EFB/AGM batteries, and how the Leon uses an EFB battery.

That sounded expensive, so I popped the hood to check mine out, see what was going on... Lo and behold, I take off the cloth shroud from the battery and it's a friggin' Duralast battery. You know, the cheap , wet cell from Autozone. And it was even smaller than the Leon spec! So I start to shop around for an actual EFB for my car.

I live in Mexico, and apparently it's pretty much impossible to get the EFB for the Leon except from the dealership, and you're going to be paying over $300 USD for one. Good thing the internet exists and I found that it's exchangeable with an AGM battery. I found a shop that sells those, to the size and specs to my Leon. Plopped that one in and... The fan has gone away.

I've been driving for a week now, the start-stop works every single time, and the fan hasn't turned on at all! (It's been really good weather). So my only assumption here is that the low voltage was triggering some sensor that made the fan remain on most of the time.

I am glad this is over.

TL;DR previous owner had a crappy battery in my car, I replaced it with an AGM and the issue went away.

 

[RUM4MO]

Good, and the AGM battery should live longer than the EFB one!

I was surprised/shocked to find that SEAT fit an EFB into the Leon Cupra, I had expected that they would fit a AGM battery, I'm sure that higher spec'd VW Golfs have AGM fitted at factory, my wife's 2015 Polo 1.2TSI 110PS SEL has an EFB and it is dying slowly, but that car is in a lower size and so cheaper than others. My 2011 Audi S4 has a AGM from factory, and it is still healthy.

 

[Deleted member 103408]

If you have access to VCDS or OBD11 I would check to make sure that the car has the correct Battery Technology set in Battery adaptation as my understanding is its used to work out the charging cycle.

 

[RUM4MO]

I agree, but it seems to be "happy" enough but maybe not optimised to that AGM battery, I'm guessing that the factory settings were left "as is" when the previous owner got that cheapy battery fitted.

 

[Deleted member 103408]

Indeed but I personally would check to make sure they had not set it to a different sort, in which case they need changing back again.

 

[Satsumomo]

Thank you! I had no idea I had to check that as well, thankfully I do have access to Carista, I'll check it out.