Intermittent Oil Warnings?

[gnetwerker]

As I was driving away from home the other night, my '04 C4S threw an oil warning light. By the time I looked at the gauge, the pressure was back up to 5 and the warning was off, but a few yards further on, it threw another. I put the car back in the driveway and took another car. The next morning I checked the oil level, looked for leaks, etc -- and found nothing. The car started up and ran fine, with normal oil pressure (which to me is 5 when cold, then 4-5 when driving and 2-3 when idling).

Clearly a little worrying, so I've been keeping my eye on the gauge lately. A week or two after the incident above, I was accelerating rather vigorously from a stop onto a freeway, and it threw a oil warning again. I quickly looked at the gauge, and it was reading zero. Oh sh*t. But I put my foot on the clutch and the gauge went right back to 5, and was normal from then on.

So, do I have a bad OP sensor, something gummed up in the oil system, or something else entirely? Any ideas? I'm taking the car into the shop soon anyway, so if anyone has an idea of what to ask about, please let me know.

[logray]

From your description it sounds to me like the pressure sender would be a likely culprit.

[wvicary]

I agree with logray, replace the sender unit and also carefully inspect the wiring terminals for corrosion.

[Loren]

Or could be just a loose connection...

[bosstucker]

I've had the exact same problem on my '02 4S (including having the Oil pressure gage read 0 bar under hard acceleration), I think it must be a loose connection to the oil pressure sender unit too, though I haven't gotten down in there to check it, also haven't had the problem in a good month or so.

[gnetwerker]

Thanks for not confirming my worst fears. I drive daily over some seriously crappy roads, so it probably is just a loose wire.

[whall]

Hopefully, you are getting only the OBC warning, which is only a polite notice to basically check your oil quantity and then visit your dealer to remediate the situation (purchase a new oil pressure transmitter).

If it is the low oil pressure idiot light illuminated - with or without the OBC warning - you should not drive any further than to get to the side of the road and shut down the engine. The idiot light is the only "true" indication of sufficient oil pressure or lack thereof. AND, every occasion of the idiot light illuminating is recorded in the engine's DME.

Bill

[gnetwerker]

WHall - Thanks for that note -- it is worth knowing that. I think it was just the oil can symbol on the OBC, and not the idiot light. I know it sounds idiotic to say "I think", but between hearing the chime from the OBC, looking at the OBC, looking at the gauge, and trying to both drive and look for a place to pull over off the freeway, by the time I could look at the idiot lights nothing was on.

[Loren]

Oil Can = Low oil pressure

[wetwilley99]

I HAVE THIS SAME ISSUE WHERE IS THE SENSOR AND CABLE LOCATED?

[logray]

Numerous threads about this. I noticed you double posted... however...

Have a look at this thread:

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