I was driving home tonight and looked down and my oil warning light was on while idling. The reserve tank was almost full and the engine was almost at operating temperature.

When I took off - only had a block to go to get home - the oil pressure came up and the light went off. At idle at the house the light came back on. Pressure is below one bar at idle.

When I turned the car off and recranked the pressure goes to 3 bar and then back to below one bar and the light comes back on.

Any ideas on what to look for would be appreciated. (I am not driving the car.)

THANK YOU!

 

Yep, more than likely you need to replace the oil sending switch. Not an uncommon issue.

If you search YouTube (no kidding here) for "993 low oil pressure" you'll see a couple of videos that should fit this behavior exactly. If they do, it's the switch. Replacement is not all that trivial. Switch itself is around $50, AFAIK, about 3 hours of screwing around as it's behind the intake manifold.

 

Thanks, Nile! I feel a lot better now. It's just like this. Is the car okay to drive??

 

Chad, I know exactly how you feel, I had a scare with that as well a year and a half ago, Especially knowing that PO already changed the damn switch (not too well, apparently).

The car is safe to drive, yes, as long as the oil level is OK. I believe that there was a DYI write-up on 993 board here on replacing the switch in the last 3-4 months.

 

Oil level equates to oil pressure?

 

I just had mine replaced when the top end was done 9 months ago. So this was a good scare. The reserve tank looked good once I was idling for a while. At speed, the reserve would go down and the light would go off. As soon as the car idled, bam, the light would come back on. I checked the oil level with the stick and everything looked good there too. I was like, what the FUCH is going on??

 

It doesn't, of course, Alex. I'm just paranoid enough to check it, just iin case, even after I was convince the fault was the pressure sender switch (which it was in my case).

 

some reading for ease of mind

https://rennlist.com/forums/993-foru...-pressure.html

 

By "check", do you mean you confirmed oil pressure with a separate oil pressure gauge?

I don't think I'd risk an engine assuming a low oil pressure indication is due to a faulty sender, even though it is the majority of the time. Do pressure relief valves fail?

 

Pressure relief valves certainly fail. Oil pumps fail too. What I am saying, at least check the oil level and make sure the low pressure is not related to low oil. Whether to drive with this light on - it's a risk, although a small risk based on switch failure mode and frequency.

But you are right in that it should be addressed, at least for peace of mind of the owner. I did and do want to let Chad know that most likely there's nothing catastrophic to fear in his case.

 

Hi. ^^^ Thats a video I took some years back.

For me it was just the OP sender.

A point of note. MAKE SURE you source the OP sender direct from the dealer. There are grey market units which are sub-par. First one I replaced was a dud.

Lesson learned, went to the the dealer for the part. My Mech swapped it out and hey presto!.

GL

 

For those testing the VDO oil pressure sensor, here are the specifications from the Porsche Electrical Diagrams and the VDO product page.

Porsche
0 Bar: 5Ω - 13Ω
3 Bar: 111Ω - 121Ω

VDO
10Ω - 184Ω

And attached is a chart I produced based on VDO's specification for values not listed.

 

Thanks for the replies, everyone. My mechanic wants me to have it towed. That's probably going to be $200. Uhg. I guess it's better to be safe than sorry. He mentioned oil pump and the relief valve. Hopefully it is neither of those.

 

Chad, AAA Plus costs $76 a year. Look into it. Tows up to 99 miles free 4 times a year.

I still think that towing it is extreme, but will not make a recommendation - it's not my car and not my money.

 

I would as well, initially with the oil level gauge immediately upon noticing a low oil pressure indication and then the dipstick.

But saying that "the car is save to drive (with a low oil pressure indication) as long as the oil level is OK" is saying that one has oil pressure as long as the oil level is OK which we both know is not the case.

Just a clarification since these threads are referred to now and in the future.