Punkin has been occasionally throwing a Failure Indicator light (a thermometor in water sign along with the FI words) at startup. The temp light would blink a few times. Then everything would disappear. Then a few starts later she wouldn't want to start. It would take three attempts to start and when she did, she'd run very lumpy. You could smell gas.
Doing some research, I found a thread on here with the exact same symptoms and a faulty temp sensor was the reason. It seems to slowly die, so sometimes it works and sometimes it doesn't. When it doesn't, the computer thinks the outside temp is -40 deg, so it remaps the fuel to winter conditions, thus flooding the engine.
I haven't found much on the actual process to change the sensor. It looks to be accessible from the front opening. I think I read somewhere that you have to drain all the coolant before replacing the sensor. My questions are:
1. Could I quickly pull the old sensor out and quickly stick the new one in without draining the coolant? Obviously I'd loose some coolant doing it this way but not that much.
2. Could I cause a hot spot in a head by doing the quick change?
3. If I refill the system after doing the quick change, would I need to burp the system?
I believe I have some good news for you. There is no need to drain the coolant in order to replace the temperature sensor. I had this job done on my Cayman last year by Porsche in Greece and there is no charge for coolant replacement (labor or spare part) in the receipt. As we all know, there is no way an official Porsche dealer is going to forget charging you for a job done or a spare part replaced on your car. The only things charged are labor for dismantling the engine cover and replacing the sensor, plus the cost of the sensor as a spare part.
I did this yesterday myself. It took 2 minutes. You don't have to access the engine from behind the seats like the other thread that shows how to do this. You can do it from underneath the car. The coolant did pour out when I did it, so be ready to get soaked and have the new sensor ready in your other hand to install really quickly once you pull the old one out. Many people say they did not lose any coolant, but I probably lost a pint. Unless you lose a lot of coolant, just top off with distilled water. The only tool I needed was a pair of needle nose pliers to pull the green retaining ring out. If you do not want to attempt it yourself, any mechanic should be able to do this if you show them where it is, so you do not need to go to a $90+ / hour mechanic or Porsche dealer. I got the part from Pelican Parts for about $15+ shipping.
biggal76 - good to hear you can do it w/o draining the coolant. Wish I would've seen your resp before I stopped at the dealer. Cost was 3x what you paid.
nikoz - while looking at the microfilm, it appears there are 2 different sensors. One in the coolant pipe and a 2nd one in the intake manifold. You probably had the intake manifold one changed, which wouldn't require any coolant replacement.
Well I've been putting the repair off for a while - had a trip to CA and a DE to prep for. Finally got to fix the temp sensor last weekend. Since I didn't find a good write up on how to change the sensor, thought I'd pass along my experience.
I wasn't too interested in getting a coolant bath down my arm and back so I wanted to do the fix through the front hatch rather than from below. The carpet is held on by 4 plastic nuts along the top of the carpet. Once the hatch was open, the sensor was out in the open. I tried to work the plug off the sensor but it wouldn't budge. Didn't want to break something, so I decided to attack it a different way - pull the sensor out of the pipe and then unplug it. As mentioned earlier, a U clip holds the sensor in place. Unfortunately, the clip attaches from the bottom. I decided to put down some rags below the sensor so if the clip came flying off it wouldn't land in some unreachable location.
Got the clip off without issue. Readied the new sensor by putting the new O-ring on and got ready to do the quick change. Pulled the old sensor out and got the new one in with very little coolant loss. Looked at the old sensor and the O-ring wasn't on. Looked below on the rags - nope. So I pull the new sensor out and check in the socket - the old O-ring is still in place. Snag it out and shove the new sensor back in. Lost about 6-8 oz of fluid.
The old sensor had the typical Porsche snap on system where you pull the square ring away and the plug pops right off. Unfortunately the snap was on the bottom side when the sensor was in place, so it would have been impossible to take off since the clip was inaccessible. So pull the sensor first and unplug it after.
It was difficult to get the clip back in place. It had to be started straight and slid on evenly. It took a few attempts but finally got it. (I was sooo tempted to try putting it on from on top but didn't know if there was a flat spot it rides in from underneath.) Once the clip was on properly, it was easy to slip the plug on. Job done. A couple of short trips to circulate the coolant and check the level.
Here are the parts #s:
Sensor - 997 606 410 00
O-ring - 999 707 508 40
Watch out for sharp edges and be patient. It's not too hard when you know how to attack it.