anolin

Driving to work today, my oil pressure idiot indicator started flashing at me. I immediately pulled over and called my local Audi guy, who after some discussion seems to think it's a sensor problem. Here's why - The sensor computer display has been pretty screwed up lately, telling me I am out of gas when I have 3/4 tank, and telling me my battery is not charging when I put my meter on it & read almost 14 volts. It also more often than not tells me I'm not using any gas during my 75 mile trip to work, which we all know isn't quite right. The oil pressure needle gauge is working as it always has for years - 3.5 bar at idle, pegged to over 5 bar when driving. Oil is fresh & properly filled. No engine noise, runs great. But I took it home anyway and parked it. So here's my list of questions -
- Does anyone really think it's a sensor issue?
- Does the needle gauge use a different pressure sender than the computer?
- Where is the oil pressure sensor located?
- Is there a common grounding point or something that all the idiot sensors use for a signal reference ?

Any help, commentary, and off color remarks would be, as always, most appreciated.

V8QinNJ

If it were "just" the oil pressure guage, the I *might* think sender. But given the V8's history with flakey instrument clusters, I'd vote IC.

That said:

The oil pressure sending unit feeds the gauge and the autocheck. The sending unit is a two wire unit next to the oil filter. There is also a single wire sender there, it is for the oil temp. The oil pressure sending until is about $150.00 and the oil temp is about $5.00.

I still vote IC.

Hope that helps.

anolin

Scott, thank you for your insight once again. So the same pressure sending unit feeds both the "real" gauge and the autocheck? Only the autocheck is giving me the idiot light, the gauge is showing good strong pressure, as usual. As I said, autocheck is giving me all sorts of false readings. I just want to make sure I have an IC issue and not a real oil pressure issue, you know?

steveneashcraft

I believe in the 1994 V8 the oil pressure sensor (2 wire by alternator) feeds the pressure gauge and a separate 1 wire oil pressure switch (triggers at 1.3 bar) feeds the idiot light.

My oil pressure gauge is pegged to +5Bar as soon as the key is turned on. I have been trying to trace the wiring. Bentley manual gives a great place to check resistance (yellow 26 pin diagnostic connector) but I can't seem to find this connector. Any ideas where to look? Thanks

V8QinNJ

The "Yellow" connector that it is asking about it on the back of the instrument cluster. The single wire is for oil temp.

HTH.