Erratic oil level sensing

Had the car serviced recently and since then the oil level sensor in the dash reads all over the place. The level on the dipstick is fine, as in full, but for that reading on the dipstick I get a readiing of half or less than half on the electronic readout. Anyone have this problem/know the fix?

Quotes source post: 13085547

Reads like the oil level sensor is bad. Briefly, it is a wire that is looped inside a plastic tube. The portion of the wire that can be immersed in oil is bare of any insulation. Current is passed through the wire for a fixed amount of time and then the resistance is measured. The resistance varies by how hot the wire gets and how hot the wire gets is related to how much of its bare portion is immersed in oil. (There is a thermister -- on its own circuit -- at the bottom of the tube to so the temperature of the oil can be taken into account.) If this wire comes loose from the post that it loops around down at the bottom of the tube the wire can move about in the oil and its heating can vary and then of course the level will appear to vary.

I wonder if Porsche has ever decided where and how to measre oil levels. In my 964 and 993 the engine had to be fully warm and you measure the oil on the dip stick with the engine idling. On my 996.2 you measure when the engine was fully warm, the car perfectly level, you turn off the engine and wait ten to fifteen minutes and then read the oil level on the guage and can confirm on the dipstick. In my 997 it was all about the guage...and I was never sure when I should read it so I was never sure what my oil reality was. Now I'm in my 2000 3.4 996.1 and the manual says I can read it on the electronic guage when the engine is fully cold...or I can have the engine fully warm and then turn it off and wait no more than 15 minutes. Both systems are giving me between one and two notches below full...and that is what I'm living with.

I never use the computer. So glad the 996 still has a dip stick! Was shocked the first time I realized that my Cayman didn't (after me spending 15 minutes looking for it).

Quotes source post: 13086205

Thanks. How do you access this sensor/loose wire?

Quotes source post: 13087283

The sensor fits into the engine from the top of the engine. Not sure if the intake manifold is in the way or not. If -- big if -- the cause of the symptoms is the sensor the old one has to be removed and a new one installed. My usual advice is to have the problem diagnosed by a Porsche tech, well trained and experienced on these cars. While I think my diagnosis is correct, I'm not a Porsche tech. I just cut an old sensor apart to see how it worked and noted based on its design possible failure modes. The loose wire in the sensor is not repairable. Likely the hook at the bottom of the tube the wire loops around has broken. In the off chance the problem is just a marginal electrical connection, you can find the sensor and check its electrical connection to the engine wiring harness if you can access this connector without excessive difficulty. Do this with the engine off and cold of course. If you can do so without risking breaking something you can carefully disconnect the harness from the sensor connection then reconnect it to remove some surface corrosion that might have developed. At the same time you can determine if the connection is secure/tight or loose. If loose not sure what the remedy would be. Be careful. The age of the car means every hose/electrical connection is fragile. You do not want to disturb any other hose connection, wiring connection to avoid causing any other problems.

Quotes source post: 13086807

The procedure to measure the oil level is not offered on a whim. With the air-cooled cars you mentioned they came with dry sump oiling system and it is correct to measure the oil level with the engine idling and up to temperature. This is only reliable way of knowing the oil level. My 2003 Turbo not only requires the engine be idling, and the engine up to temperature, but the car reasonably level, too. Once up to temperature I can check the oil level at a stop light. After a drive say to the office I check the oil level while I let the engine idle to cool the turbos. On the road I check the oil level while the engine idles -- again to cool the turbos -- on the gas station drive just before I fill up the fuel tank. OTOH, my 2002 Boxster the oil level can only be checked if the engine is off and has been off for a time. How much time depends upon how warm the engine was when it was last shut off. Fully up to temperature I can check the oil level with just a 5 second wait -- this the time I think current is supplied to the bare wire immersed in the oil and then a resistance reading is taken -- after the time it takes to gas up the car. I am quite familiar with the fact that at other times the wait time may be a long time so I do not bother with taking an oil level measurement then. I take one before the first start of the day. Then maybe at other times during the day, after the engine is up to temperature. Certainly after I fill up the gas tank and on the road, on a road trip, I check the oil level after every fill up even though I might drive the car enough miles to fill up 2 maybe 3 times a day. Might mention while my Boxster has a dipstick I seldom use it -- can't remember the last time I used it -- but instead rely upon the electronic oil level sensing/reporting system to check/monitor the oil level.

Quotes source post: 13087283

Post #4 here http://www.renntech.org/forums/topic...king/?p=255762 Bank 2 intake manifold has to come off. The sender is very long so you also need to lower the engine before you can remove the sender completely. Do you always measure the oil level under the same condition? I found the gauge to be very accurate if I read the level in the morning before I start the engine.

Quotes source post: 13088150

Yes I do, in the garage before I start it up, engine cold. Always have done it the same way, always been fine.

Quotes source post: 13088629

You mentioned the car was recently serviced. Did the service include disconnection of the DME or the X59 connectors in the engine bay (big round ones on the rear right)?