Porsche Enthusiasts Club Forum

Hi everyone.
Wondering if anyone can help me with an answer. I've got a 2000 plate 996 C4 which has been very well looked after and runs smoothly.

However, yesterday for a fraction of a second, the red oil warning lamp flashed and disappeared. I thought maybe it was my imagination but it did the same thing twice today. It seems to do it when I'm near the end of my hour drive home from work, and from what I remember, when I'm either at crawling pace in traffic or at a standstill.

I checked a few things once I got home today. The digital oil level readout seems to show full, and I checked the dipstick in the engine and that shows the levels are full also. I had the car serviced a few months ago and had the oil changed. Still looks clean, and as far as I can tell, there are no leaks.

I've read on various forums that some Carrera models have a digital display oil pressure warning message that could come up as a result of a pressure sensor/sender malfunctioning, and people not thinking that's a big deal. However, I also read that if the red circular oil light flashes in the dash (which is the only thing I have, since my car is older than the models that display warning messages) this should NOT be ignored.

As far as I can tell, the car is running as normal. Oil pressure seems responsive relative to RPM and idle (although the longer the engine is running, the lower the oil pressure when idle. In the past, after coming off a motorway and being idle in traffic, oil pressure would read around the 1 mark. I noticed recently that it reads just below 1. Is this normal?

As I said, the light barely flashed so far, but want to ask if anyone knows what it would be before the engine gets damaged. At the same time, if the oil levels are where they should be then is the warning light just a glitch? Any thoughts?

Thanks to all in advance.

Not sure if it's related, but you said it was serviced the other week and I usually look for the cause and effect when finding out the reason for a recent problem. In other words, what changed? Anyway, this brings me to my question, what oil was in the car before the service and what grade is in it now? Could it be thicker/thinner?

This really is a weird one. I took the car to an official Porsche garage today for a diagnostic and they said that there isn't even an error code logged that the oil light came on briefly. Over the last few days I noticed that the light came on when the revs dipped below normal on idle in traffic (at one point when parked at home, I could hear the engine was struggling not to stall… complete with trembling interior lights) but according to Porsche, there is nothing coming back in the diagnostic and they can't find anything wrong. All they did was remap the throttle management, but said that this isn't really something that would rectify whatever is wrong.

They checked the oil level and it's fine, the oil pressure is as normal according to them also, so I have no idea. They said to come pick it up and keep an eye on it for the foreseeable. I'm guessing the engine won't blow up as long as there is oil inside (which is at optimum level).

Not quite sure how to take this news. On the one hand, it's good news that I only have a bill for a diagnostic… on the other hand, whatever it is, has not been sorted.
Still no answers to this!

From reading that, it sounds non oil related and more like idle control or the MAF on its way out? The light is only flickering when revs dip below normal idle? It's hard to fix an intermittent problem, you really need whatever it is to fail and break completely.

Thanks. That fills me with joy!! Haha.

Correct. The light flickers when revs dip on idle.

Can I ask what a MAF is? I'm picking it up in the morning... I might suggest it to them if I can convince them I know what I'm talking about! Haha

Ah got it... The mass airflow sensor. Wouldn't it be flagged during diagnostic if it wasn't working properly?

Had a different issue a few years back and as soon as they plugged in diagnostic, they knew an oxygen sensor in the engine was failing.

Sorry, yes it's the mass air flow. The problem is its not failed completely so you won't gt codes. Something is causing the idle to drop and pick up again. I'm only guessing, the OPC are better equipped to diagnos.

So I went to pick my 996 up from the Porsche dealership a couple of days ago, and hats off to them... They said that because they couldn't identify anything wrong, from a customer service point of view, they were going to waive the charge for the diagnostic & the technician spending 45 mins on the car, as a sweetener so if I had to bring the car back, it wouldn't be such a blow.

Been driving the car for a couple days now and could see that the throttle remap was working the engine over better (slightly higher idle revs). However, on the way home this evening, I got the same light flash for a split second. I'm guessing until something 'goes' it will be ok to drive. The diagnostic didn't even register that the light had previously come on, so no error code to identify the cause. All they said in parting was to just keep an eye on it. I'm sure they would advise not to drive it if it was potentially damaging?

Aye, I don't think it's actually low oil pressure that's the problem, from the description you gave. I think it's the idle dropping when you come off the gas.

Yes I think you are right. Not an oil issue at all. For whatever reason, every now and then when I come off the gas the idle drops below normal but comes straight back up again. That split second it's beliw revs must make the ecu think that the engine is seizing up due to lack of oil, or something.
Hats off to Porsche East London for waiving the diagnostic charge and for not scare mongering me into spending money on what "might" be the cause.

Hopefully it's just a glitch that fixes itself.

I think that as your revs are dropping for that short time the oil pump revs drop and hence your oil pressure drops and the system sensors are picking this up real time to give you this flicker that your experiencing.
In my opinion you need to investigate and rectify why this drop in revs occurs because it's not supposed too, you are experiencing low oil pressure for that very short time which is not good for any engine.
If as you've said the diagnostics aren't picking up an issue then it's possible that the various controls that influence this condition aren't being activated. In which case I'd be looking for a vacuum leak or maybe you've had some bad fuel.
What did the Porsche techs say about the revs dropping?

As far as what they told me was that they couldn't find anything and to just keep an eye on it. They remapped the throttle so even on idle, the revs are slightly higher. I asked about the oil pressure and he said as long as there is pressure when I'm accelerating then that is fine. They're as stumped as I am.

Bad fuel had crossed my mind but I always put shell v power in and it's been a couple of tanks since.

So as a result of what the OPC did for you, you no longer get the oil light "flickering on" condition any more? If that is the case great and I agree with what you've been told, however if it's not the case and it still flickers on then I would continue to look for the cause.

Since getting the car back, it flickered once. The remapping has definitely made it better but still happened once. Unfortunately, because no error code is logged for diagnostic it is pointless taking it back just yet. I think it was you that said it is difficult to find & fix an intermittent problem, so until it whatever it is completely fails, I won't know

OK I understand where you are on this but for piece of mind have the air intake filters, engine breather and the EGR valve checked to ensure there's no resistance across the first two and the latter is working correctly and not blocking up in any way. And get those vac lines checked for leakage. Talk to your OPC about these, if they dismiss them, all to the good.