Every now and then I'll hear the fan in my Octavia randomly turn on while the car is off. If I u lock the car it stops the fan running. When I turn on the ignition I will get a 'battery low' warning message. It's annoying cause if I'm not around the car and the fan comes on it will drain the battery and I have to jump start the car. Any help is greatly appreciated. 

Assuming you have a diesel......dpf

1 minute ago, MarkyG82 said:

Assuming you have a diesel......dpf

Sorry yes it's a diesel. I should have mentioned that in the post. The car has been off and locked for the last 5 hours and the fan just started up again. If I unlock the car it stops but it's starts again when I lock it. Seems the only way to stop it is to unlock the car and turn on the ignition.

What sort of trips do you do? Sounds very much like the dpf is trying to do it's thing.

Just now, MarkyG82 said:

What sort of trips do you do? Sounds very much like the dpf is trying to do it's thing.

My work drive is a 80 kilometre round trip, so 40k in the morning, 40k in the evening minimum. 90% of it is on the motorway. 

That should be ok for a diesel. How many miles has the car done, how long have you had it and have you always done those sort of trips?

12 minutes ago, MarkyG82 said:

That should be ok for a diesel. How many miles has the car done, how long have you had it and have you always done those sort of trips?

I was thinking that should be ok for a diesel too, I very rarely do short trips in the car as I know it's not great for a diesel engine and I like to take care of it as I love the car. 170,000 miles on the clock. Have had the car 4 years. 

170k could be the life of the dpf?

Try and scan for a fault code with vcd's or similar. Something is very wrong. If its been standing for 5 hours the fan shouldn't come on randomly.  Maybe the battery is failing and confusing the system.

9 minutes ago, ords said:

Try and scan for a fault code with vcd's or similar. Something is very wrong. If its been standing for 5 hours the fan shouldn't come on randomly.  Maybe the battery is failing and confusing the system.

I'm starting to think that the battery is the problem. The alarm just randomly came on now as well. The car will be parked up for the next week as I'm away so I disconnected the battery and will try a new one when I get back.