Today, I noticed that the cooling fan of my 2002 S40 is staying on a couple minutes after I turn of my car. It's been much cooler lately then compared to the summer, so this has me confused. A search yeilded that I should clean my MAF sensor. I guess that's the first thing I'll do. However, if that doesn't do it, does this symptom relate to any other problems with the S40?

 

Check engine light on?
You might have a bad ECT or thermostat.

 

MAF, MAF, MAF, MAF!

The only time mine ever ran on was when I ran the car without the MAf plugged in (on accident!)

Clean it and reevaluate.
There is a how-to link in the Sticky Frequently Asked Questions thread.

 

Had the same issue and it was the thermostat

 

Thanks for all the replies. Well, I finally found some time to clean my MAF sensor (family calls). This was after my wife was driving it the other day and said that the car started to "overheat" before she turned the heater on full blast and rolled down the windows and then it was all good. So I went and bought the MAF cleaner and cleaned it up. I drove it to the store the next day and everything seemed fine. I parked and sure enough, the fan stayed on. My first thought was that I guess I need to buy a new sensor. Then, on the way back, I turned on my A/C and hot air started coming out and noticed my temp gauge started to rise. I turned off the A/C and it went back down. I turned on my A/C a minute later and had no problems and worked fine. Very strange. So now I'm thinking it's something a little more serious. There are no check engine lights or anything else on. Any other thoughts and should I check the codes despite not getting any check engine lights? One other thing I left out previously was that I noticed my fan was running louder then normal while I am driving, but I figured that went hand-and-hand with it staying on after I turned off the car.

 

It could still be the ECT or maybe the cooling fan is not turning on all the time.

 

I'll let you take over. This is out of my league.

 

Ok, thanks. I guess I need to find out how to fix the ECT. Is it usually a good idea to replace both the ECT and thermostat at the same time?

 

Yes it is a good idea.

 

I got away with just replacing the thermostat.

 

Yeah, I just priced them at Autozone and it would be smart just to try the thermostat first:
$65 for the ECT
http://tinyurl.com/yjvj6vt

compared to just $6, $9 or $10 for the thermostat:
http://tinyurl.com/ykxftlz
By the way, what's better for our car - 160, 180 or 192 degrees? Or does it matter?

 

Well, I just got the thermostat and will know if that does the trick when I finish my commute tomorrow morning. I did notice one thing on the way home that might help diagnose the problem if that's not it. My temp gauge would raise when I was stopped at a red light just idling. I even had to turn off the A/C if I sitting too long. The rpm's weren't up or anything, just the temp gauge. It would go back down after acceleration. Tech, does that sound like anything else to you or does that still narrow it down to the ect and/or thermostat?

 

Same thing.

 

It's fixed! The thermostat seemed to have fixed the problem. Thanks to all that helped! Total cost to fix my car was $6 for the MAF cleaner and $10 for the thermostat. Who knows what it would have cost to take it somewhere.

I also noticed my radiator fluid was very low. I hope there's not a leak, but that shouldn't be too bad. I don't know if that's what helped ruin the thermostat, but probably something to mention to check for in case someone else that may search and come up with this thread in the future. Anyway, thanks again.

 

Huzzah!

 

Now hopefully the ECT does not go bad in a week.

 

Yeah, that would be some good luck!

 

Congrats on the fix! So the thermostat was the problem then. I have had the same symptoms, except the temp gauge never deviates at all it gets to optimum temp and stays there. What I have is the idle is abnormally low.

 

Are there any YouTube tutorials on this? My fan ran for over an hour after I cut it off and it killed my battery completely. I keep charging the battery and every time it gets a little juice the fan comes back on and kills it again so if there is anything I can do to get the fan to stop please help a girl out. This is a 2009 S40 T5

 

Your fan relay is stuck on. Just look for the relay labeled fan in your fusebox, and pull it... the fan should stop. Of course, you need a good relay, but you should be able to swap one over from another position (Volvo uses the same relays for many things). If the relay you remove is for something "optional" (like the horn), then you have bought yourself some time while you order the replacement relay. Sorry, I don't have a diagram for your particular car to tell you precisely where that relay is.