Hard start problem & radiator fan stays on 2004 S40

FunkadelicxS40 · Post by **FunkadelicxS40** » 30 Oct 2019, 02:06

So the other day I tried to start my 2004 S40 Around noon after it sat over night and I could not get it to start. After 3 goes I attempted to give it some gas while cranking and it started to sound like it would turn over but when I took my foot off the throttle it died. Each time after turning the key to the off position the radiator fan would stay on until I turned the key to the on position. I had to unplug the battery to be sure it would stay off and not drain it. I left it and caught I ride with my gf. I attempted again the following afternoon and it had a similar difficulty starting it and fan staying on but the third time after pumping the gas I got it to start, but I could smell gas from behind and around the car. This time when I turned it off the fan did not kick on. I have had occasional difficulty starting it in the recent past, but didn’t think anything of it cause it would only usually be when real cold and only be once or twice before starting up fine. I’m wondering if this is a more serious problem or just an engine coolant sensor or fuel line issue or possibly MAF sensor error. Any ideas before I take it down to a mechanic? Had lots of small repairs recently and not Trying to dump a lot of money if I can diagnose and fix myself or save a bit. Any ideas appreciated thanks!

Post by **jimmy57** » 30 Oct 2019, 11:46

If the engine coolant temperature sensor (ECT sensor) is unplugged, has corroded connection, or is faulty then the ECM will run cooling fan continuously with ignition on and then for up to three minutes once ignition is switched off. The engine will get fueled for a 0 degree C start which will easily flood engine if it fails to start up on the first attempt. The ECT sensor is in the thermostat housing.

FunkadelicxS40 · Post by **FunkadelicxS40** » 30 Oct 2019, 12:09

That is likely the case, although the fan only kicks on when I turn the ignition off completely. It turns off when ignition is on. It looks like it is connected and couldn’t see corrosion but looked like some spots on the outside of the connector. I’m assuming this is the OEM part which is now 15 years old. Is that about the average life of the sensor? I’ve been told to only replace it with another OEM sensor, but the range of these sensors is quite wide seeing some as cheap as $10 and up to $110. Is this part something I should leave to a professional to exchange or is it easy and safe enough for a novice to replace?

Post by **MoVolvos** » 30 Oct 2019, 13:16

You are in Knee Deep decision on those parts. Do Fries Come With Any Of The Brands?

Post by **alschnertz** » 30 Oct 2019, 15:04

Are you getting any codes? Not convinced that it's the temp. sender yet.

But still, a quick search of FCP's website revealed this temperature sender...
https://www.fcpeuro.com/products/volvo- ... -9125463oe
Be sure to double check that this fits your car if you elect to just throw a part at it.

It looks like the price could range from $63 for a factory part to $23 for aftermarket.

FunkadelicxS40 · Post by **FunkadelicxS40** » 03 Nov 2019, 21:34

I didn’t get any codes back from my OBD2 reader. I gave it a try the other day and it started up fine first and second try, but I don’t feel secure in driving it without getting it checked out. Must be something with the air to fuel ratio causing it to struggle starting.