Need advice on CEL light

[ryanwise]

This is probably a question without a real answer but I thought I would tap the vast knowledge of this forum before I take action. Maybe somebody has had this experience and can point me in the right direction. I just did a DE at Sebring last weekend. The car handled flawlessly. On the way back home to Tampa, the CEL light came on. The car continued to run fine and you would have never known anything was wrong. While I had not used the computer to check MPG , I had noticed the car seemed to be using a little more fuel the past few months before this past weekend. I know since I have owned the car for the last 4 years, at 70mph, the computer was showing about 27+mpg and once the CEL came on and I reset the computer, I was reading about 23.5mpg. So , I have a CEL and Im losing MPG. The question is............do you think I should spring for a code reader and try to make the diagnosis myself and relay the info back to the forum for a self fix, or just take it to the dealer.

[mikefocke]

What would be your expertise to fix it once you had the diagnosis? If probably none, then let the dealer do the diagnosis since that is bundled into his flat rate for the part replacement.

If you have some desire (and sometimes that is all it takes) or some experience and tools, then is there a buddy that would have a code reader for you to get a rudimentary code readout and then see what it might point to before you tried a fix? Or an autoshop that would loan you one? Takes 5 minutes max to read the codes.

As for buying a code reader, an Actron is basic and works on lots of cars, a Durametric much more capable and Porsche specific and for long term P-car ownership the thing to have (installs on a laptop). Dealers buy or rent even more powerful diagnostic computers from Porsche.

[ryanwise]

Thanks Mike,

I donmt have a problem getting into the car..........my issue with this one is the loss of MPG which Lord knows could be anything in the fuel mgmt system. I'd get the code, but not really sure where to start looking . Dont want to start throwing parts at it. Hate to say it, but the dealer may be the best alternative.

[Mark_T]

Your mileage definitely seems low. I just did a mileage check and on an 800 km highway round trip I averaged 34 mpg over two tanks of gas. This of course did not involve any spirited driving - just a steady speed around 100 - 115 kph (60 - 70 mph.

It's funny, even though we are a metric country, and have been since the 70's, using liters per 100 km's means nothing to me - I always convert to mpg. I even wrote a small computer program in C that allows me to input km's and liters and have it converted to mpg and then save the data to a log, calculating an ongoing average.

[ccstud17]

go to any Checker, O'rileys, Advanced Auto, Napa (any big chain auto store) and they will use a simple code reader (OBDII) and tell you the codes. Takes them about 5 minutes
write codes down
come on here search the codes, and then you will see what is needed.
lower MPG could be as simple as a dirty MAF ($6 fix)

[ryanwise]

Well I really feel stupid, but relieved at the same time. I just went to get gas as I was down to about a quarter tank. Filled up, and started home. About a 1/2 mile down the road.....the CEL went out. It was the damn gas cap. I didnt "click" it when I got gas at Sebring for the ride home.
All is well guys.........................

[kk2002s]

Don't feel stupid. The first car that I owned that generated a CEL for loose cap, did so. I panicked and did all this research and that's when I learned about it.

Here in NJ, attendants have to fill gas and I have to make sure I pay special attention that I hear the click and double check if in doubt