Oil Pressure Switch/Gauge not working

[darrinsmith]

Hi

I am having some oil pressure gauge woes in my 99 3.4 996.

When I put in the key and turn the car to on, the oil pressure gauge on the dash goes straight up to the top.

Starting the engine makes no difference, it's always above the 5.

I've checked the connections to the switch and they appear correct (small to small and big to big) but I swapped them just to be sure - no difference.

So now I need to trouble shoot the sender.

Can anyone give me the procedure? I assume I can check the resistance with the engine running and stopped to see if the sender is cactus.

I had some work done on the transmission so I suspect either the sender got damaged, or they broke the wiring when putting it all back together.

If the sender is good I assume I can also do some resistance type checks at the instrument panel end.

It looks like something is grounding along the way :-( but I can start down that route once I've verified the sender unit.

BTW the oil level check bar graph at start-up is working fine and corresponds with the dip-stick level perfectly.

Thanks again!

DS

[rb101]

Your oil pressure sensor has gone bad. Replace it. I doubt that transmission work could have damaged the wiring as it goes into the engine harness not near the transmission.

[ericinboca]

Your oil pressure sensor has gone bad. Replace it. I doubt that transmission work could have damaged the wiring as it goes into the engine harness not near the transmission.

Rick is likely correct, but check the connection on the sensor. I installed a 996 sender and a gauge in my 986S race car, and sometimes the connection comes undone at the sender - when that happens, it registers above 5 all the time.

[darrinsmith]

Surely someone must know what the normal resistances are for the sender though?

Anyone?

Thanks

DS

[Loren]

Surely someone must know what the normal resistances are for the sender though?

Anyone?

Thanks

DS

It is going to vary with oil pressure.

These are a common failure - I would just replace the switch.

Porsche has changed the part 2 or 3 times. The latest version is: 996.606.203.02 Oil pressure switch -- US MSRP $66.60

[solent]

Looks like my sender went bad also (2002 996 Targa 3.6 6spd). How easy is it to replace ? I didn't see anything in DIY section ? Perhaps I should try and clean the contacts first ? On way home today pressure dropped to zero and warning light came up on dash - then it jumped to max and stuck there. Car runs fine - no leaks (53Km). Previous owner reported intermittent issue to dealer last year - (sticking at max) but I guess chose not to replace.

thanks

[TSC85]

Solent,

http://forums.rennlist.com/rennforums/996-forum/505634-oil-pressure-sender-unit-replacement-diy.html

Not hard to replace, don't waste your time with the contacts if the problem has already been made before since they probably already did the contacts. It only 50 to 60 bucks, I'm about to do mine as well.

[logray]

A possible time saving tip on this. I just had my mufflers off to check my spark plugs. Removing the mufflers is not that difficult.

Once you have them out it is very easy to reach the sender with a hand tool, a stubby or even normal wrench would probably work. Probably wouldn't need any crazy extensions or crows feet...

[996electric]

Is for a correct function of the oil pressure sensor the oil switch connection necessary?

I just put a resistor on pin 16 and 17 and nothing real happened. It should be 19 Ohm without pressure, but it is constantly over 5.

I don't have the engine in the car anymore, so the question is which signal is needed additionally?

[Alfredo Aparicio]

Hello I own a 996 2001, and the oil pressure gauge stays all the way down after I start the car and barely goes up when I rev it up at the same time the engine sounds pretty bad, what can this mean ?? 

[DBJoe996]

It sounds like you have no oil pressure.  Do not run your engine!  You need to investigate your engine and lack of oil pressure.  What type of oil are you running? When did you last do an oil change? Have you manually pulled the dipstick to check  your oil level? What type of oil filter are you running?  Have you done anything to your engine lately?  This does not sound like a problem with your sender unit....it sounds like your engine is lacking any oil pressure and it will seize if you run it again, or spin the crank bearings, or seize a piston in the cylinder.  You must do everything  you can to find out what is wrong before running the engine again.  Maybe the oil pump hex drive has broken.  Maybe the oil pressure relief valve is stuck.  Maybe your oil filter is clogged.  Maybe your oil pickup tube in the oil sump is clogged with debris.