Service engine soon, very habitual, depends on weather
 

Hi all,

My service engine soon light is coming on just about the same time every morning. From home I accelerate up a slight hill for roughly a mile or so. Then I hit the down side and just let it coast.

on very cold days, nothing special happens.

on warmer days, say in the 50s or higher, the service engine soon light will come on. It also sounds like a fan kicks in underneath in the front passenger side of the car.

After a few mins if I am just city driving - it goes away and usually does not come back on. If I get on the highway it may stay on for 2 or 3 miles or until I stop the car.

What is going on? Like I said on very cold days this never happens. These warmer days it kicks in just about the time i start to coast down the hill.

If I turn the car off and on, the light is off for a while. May come on later but not for long. Most time never comes back on.

Should I be worried, is this something I can live with or get fixed now. Will a technician be able to 'read' what is going on if the light is no longer on?

thanks for your time.

The code will stay in memory and can be read as long as battery hasnt been disconnected.

Several DTC's will turn the fans on so that is common. Codes like some of those for O2's are common to come and go.

One thing I would suggest is put information about the vehicle in your signature.

Definitely happens when 'coasting', it happened again today and the weather was in the 60s. Glad to know the 'code' will stay around, so I'll have it scanned to find out what the issue is soon enough.

Another question, how often should we have the fuel filters changed. Im not sure this has been done in 30k miles.

fuel filter
 

Every 12 15k is good as long as you run good gas and not let it get to low...

Ok that will most definitely be on my short list of things to do asap. I have a whine in the back and it may be the fuel pump having to work hard due to a clogged fuel filter. Just my uneducated guess. Thanks for the advice!

had the car scanned. Turned out to be a vacuum hose unattached from the EGR valve. No more service light!