muhammadc

'94 100CS, 91.5k miles, driven about 250 miles in 100-110deg temps, 80-90mph... final 30 miles, the oil pressure warning went off. Gear selector lights flashing, check engine light flashing quite rapidly along with a ticking sound, and the oil pressure warning light on the information display. Pulled over and did some visual checks for any oil leaks or whatever. Everything looked fine but I really couldn't see if there was *any* oil in the car... with low light, fresh oil.

Started driving again, found all levels to be normal... engine temp, coolant temp, oil pressure (100CS has the oil pressure gauge)... but after 5 miles it went off again. Stopped the car, for maybe 5 minutes, started again, made it to a gas station. Checked oil clearly this time, obviously full... all leading me to believe that it's the oil pressure sensor causing the alarm, not the actual oil pressure. Driving another 25 miles or so, under 2750RPM, the alarm didn't go off again.

Where is the oil pressure sensor located? (I don't have my Bently here with me.)

Any thoughts? TIA...

Seattle Scott

Remeber I have a '97 not a '94 but here goes.

Here's the Bentley and a picture of the one I know about. General location is rear driver side head :

<img src="http://pictureposter.audiworld.com/12414/oil_sensor1.jpg">

Connector rubber boot almost dead center of picture.

<img src="http://pictureposter.audiworld.com/12414/oilpressure2.jpg">

I drove off once with the oil pressure connnector removed. After 20 feet of travel an "oil can" appeared in the "engine display" (where it usally says OK right after starting), I heard a high pitched alarm I think. Backed into the driveway and reconnected the oil pressure electrical connector.

The part I don't like about this (and I hope it's normal) is the flashing lights. Maybe that's a feature that was taken out or I forgot about it.

Have a look, I'll keep my eye out for more messages and look at my car.

Seattle Scott

There is an oil pressure switch in the system too. Not exactly sure where, some data indicates near the oil pressure sensor...

<img src="http://pictureposter.audiworld.com/12414/oil_sensor2.jpg">

Don't have a clue where this one is :

<img src="http://pictureposter.audiworld.com/12414/oil_sensor3.jpg">

Bentley Stuff :

Switch-----------
.3 bar integral with oil pressure sensor(connection WK)---Switch opens at 2.2-6.5 PSI

.9 bar switch(grey insulation)---Switch closes at 10-39 PSI

2.5 bar switch (red insulation)---Switch closes at 10-39 PSI

Sensor Resistance

Checking 0-5 bar oil pressure sensor (with 0.3 bar oil pressure switch)


0 bar 5-13 ohm
1 bar (14 PSI) 44-52 ohm
2 bar (29 PSI) 78-86 ohm
3 bar (43 PSI) 111-121 ohm

If the cables to the oil pressure sensor are installed incorrectly, the Auto-Check-System will display the engine oil pressure warning symbol (oil can).

Note: If oil pressure is excessive (oil pressure relief valve jamming or incorrectly installed), the hydraulic valve lifters will be subjected to excessive pressure. The engine will cut out shortly after starting and, when attempting to restart, the starter motor will rotate the engine noticeably faster due to lack of compression.
Oil pressure sensor/switch: 0-5/0.3 bar
Oil pressure indication 0-5 bar

April

Seattle Scott has some good info. You're on the road I take it ? That sucks.

My first inclination would be to say that the pressure sender is bad. My Alfa has Bosch senders that are a PITA. They go out all the time ( 5 in 226,000 miles ). You should be able to get one from most good sized parts stores.

If both the warning light and low pressure coincide, then you have problems. IMHO do not drive the car any further if possible.

There is oil in the galley when you look down the oil cap ? Means oil is moving in the engine - whether it is at sufficient pressure is another matter, but at least it's getting there. Is there an extra ticking sound when revved ? Almost like bad gas or a sticky lifter ? Any funny smell ? Either burnt oil (or anti-freeze) ? Burnt oil means something has seized or is about to - such as bearings, etc.

MikTip

<center><img src="http://home.ec.rr.com/miktip/oilpress.jpg"></center><p>

muhammadc

Everything else seems normal. No oil leaking, no burning smell, no ticking, no difference in performance.... nothing. Pressure runs about 5 bar at load, which is normal for the 12v V6. Forunately, I have the oil pressure gauge and not the voltmeter (replaced oil pressure gauge in '95 I think... how dumb) so I can actually know that the pressure is fine. Already had an appointment at the German indy shop here Monday/Tuesday, so I'll have them *try* to find the cause.

Nickolaj

I now experience the same problems with my Audi 100S (94). When we take it for a long trip the oil pressure sign can sometimes go on with the check engine light flashing rapidly along with a ticking sound and some other warning lights also flashing. Quite scary! Pulled over and called AAA that checked the engine and said everything was normal (probably a chip error they said) and that we could continue driving. After 20 miles again the same happened.
Got it checked at the dealer that just said that the oil pressure is in order. The dealer was more interested in fixing another error from the EGR valve that we had seen coming on two times during the last month, this he wanted $ 770 to fix (just for cleaning the EGR port). I refused and said I only will have them clean the EGR valve when the check engine light was on more often.
When I got to pick up the car the check engine light was of course constantly on. I bought the repair manual and found out that they unplugged the EGR solenoid valve in order to make the light on constantly. I am not using the dealer anymore.
I cleaned the EGR port this weekend with the help from this forum and saved the money.
But when testing the car I can still trigger the same problem when running the engine for a long trip, where I get the oil pressure and check engine light flashing rapidly along with a ticking sound. After restarting the engine everything is OK.
What was the problem in your case?

Thanks

Nickolaj