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Low oil pressure light on 98 Audi A6

When this light comes on while driving why does the RPM indicator fall to zero and why does the air conditioning become warm? I checked oil level and this is fine, is there any harm if i continue to drive? Light only comes on after driving for approx. 15 minutes.

While it may be a result of some electrical problem causing all 3 symptoms to appear at once, you must get this checked immediately, in case there is an oil pressure problem. An oil pressure problem can quickly destroy your engine.

I would think they have a common cause, but no themselves causing the problem.

So you suggest not an issue? I think it is only a bad sensor. But Why, does the RPM fall to zero? Do you think a mechanic can just disconnect the sensor?

There’s no way to tell from here, you need to have a mechanic check the sensor and the actual oil pressure.

Doesn’t your owner’s manual tell you to stop immediately when this light is on? If so, why are you ignoring that and risking major engine damage?

The manual does state this. It states to check the oil level, which I did, and it is fine. I’ve had other sensors come on, such as brakes and ABS. I had my mechanic check these out and they were only sensors, no need for any type of fix. It is weird because the low sensor light only comes on when these other two sensors go on. This is why I think that the problem is not serious. Wanted to see if other Audi owners experienced this problem.

As Audis age, they are subject to all manner of strange, seemingly phantom electrical problems. Unfortunately, these Audi electrical problems are frequently difficult to trace easily, and finding and fixing the problems tends to run into very large sums of money.

While the cost of solving this problem may not be practical, given the age of the car, I suggest that you try to locate an independent foreign car specialist who is patronized by lots of Audi owners. Someone who is familiar with the unique quirks of these cars may be able to fix it at a cost that is not prohibitively expensive.

I know this does not make any sense, but the problem is a faulty ABS computer.
When it goes bad, it causes all sorts of weird electronic malfunctions throughout the car.
Trust me on this one, I’ve seen it before on VWs and Audis.
A new ABS module is very expensive, but there are companies out there who will rebuilt your existing unit at a very reasonable cost (~$200).
Try www.bba-reman.com
I’ve used them in the past with good experiences.

Not surprising, VW/Audi is know for weird ailments…

Thanks for your response. But does this have to be fixed? Am I causing any damage? Does this sensor really control the oil pressure level? i only use the car to go back and forth from train. Love the car , low miles (87K) But don’t want to dump $$$ in.

The sensor doesn’t control oil pressure, it monitors. And yes, you need to fix it. Ignoring/disconnecting it is like taking the battery out of your house smoke detector that keeps going off when you cook…solves the problem short term, but you may REALLY need it some day.

Texases has given a very good explanation of why the OP either needs to fix the problem or deal with the possible destruction of his/her engine from low oil pressure.

Please note that I did say possible destruction of the engine. As happens so often with Audis as they age, the actual problem can be very difficult to figure out without spending BIG bucks.

I really apprciate the very helpful fedback. Right now i am going to “roll the dice” and leave things the way they are. Due to current economic crisis I just don’t want to sink funds into this vehicle. Your replies have put some of my concerns at ease, But I do understand that potential problems may lie ahead. Thanks a bunch.

Are you sure your not getting the low oil “LEVEL” light?
The low oil “PRESSURE” light is generally red and says “STOP”.
Like most German cars of the era, you have sensors for both level AND pressure.

The oil LEVEL sensors are known problems.
Sounds like you need an oil level sensor/sending unit.

I too am going to suggest an electrical problem. That would be the only thing that could cause the tach to drop to zero while you continue to drive and it could also cause the AC compressor clutch to disengage which would cause the AC to go warm.

I’d be inclined to go to a schematic and look for a common circuit.

Owners manual states that it is low oil pressure. I have been checking oil level regularly, and it is fine.

If I continue to drive this vehicle without resolving this issue, am i causing the engine any damage? When the sensor comes on and the tach drops to zero is that doing any harm? i appreciate the feedback.

Can we try to dispel the confusion here? Your oil level can be very normal, but if the oil pump is not functioning properly, that oil is not being sent to the extremely sensitive bearings, and severe damage can result. In other words, a full crankcase is not an assurance of a functioning oil pump.

Yes, it is very possible that an electronic glitch is causing an incorrect reading of the oil pressure, but looking at the dipstick is not the way to verify whether the oil pump is functioning properly. If the problem is not of an electronic nature, and if the oil pressure is indeed low, major damage to the engine will result.

The short answer is no, you’re not doing any harm.

However, as some have stated above, when the oil light comes on there is no way to be sure it’s just an electronic glitch or if your oil pressure is actually low.

Per my post above, this is a common issue with these cars and relatively cheap and easy to fix. If you check your oil level regularly, you should be fine. But nothing in life is guaranteed (except death and taxes).