Intermittent "Oil Pressure" light on A4 8E 1.9 TDI

Hello,
'On our Audi A4, manufactured in October 2001, with a 1.9 TDI engine, 130 horsepower, and a 5-speed manual transmission, the oil pressure light occasionally illuminates.'
The oil pressure switch has already been replaced, but unfortunately, it wasn't the cause of the problem!
The error memory is also clear, with no entries.
The oil is filled up enough.
The engine has 90,000 kilometers on it.

Does anyone have any ideas on how we should proceed?
Possibly a known issue?

Thank you very much.

Hello, does only the warning light illuminate, or does the warning buzzer also sound at the same time?
If the oil pressure is too low, both of these things should happen.

If the lamp turns on without a warning sound and without any error messages in the memory, there might be a problem with the control unit's circuit board.
However, I'm currently not sure whether a lack of oil pressure triggers an error message.

Please have this confirmed or refuted by others. For example, @Sebastian.

If you want to be absolutely sure, simply connect an external oil pressure gauge to the engine and check the oil pressure there. It should have a minimum pressure of 2 bar when idling.

Best regards, Jochen.

Thank you, Jochen.

The bell rang, too. I forgot to mention that.
What could be the cause of low oil pressure?

I'm leaning more towards an electrical fault.

Hello,
It might also be due to the oil itself, or the sludge buildup within it. In the Passat forum, there are some examples of drivers who primarily use their cars for short distances and/or engines that received the wrong type of oil, and in those cases, the oil pumps failed repeatedly.
Do you drive mostly short distances? What kind of oil was/is in it? Have you ever opened the oil filler cap and checked for oil sludge? Do you use regular gasoline? Greetings, haithamina.

Quote:

I'm more inclined to suspect an electrical fault.

Why is that?

If the oil pressure sensor is working correctly, I would strongly recommend checking the oil pressure as soon as possible, because the oil pump might be about to fail.

Hello,
It might also be due to the oil itself, or the sludge buildup within it. In the Passat forum, there are some examples of drivers who primarily use their cars for short distances and/or engines that received the wrong type of oil, and in those cases, the oil pumps failed repeatedly.
Do you drive mostly short distances? What kind of oil was/is in it? Have you ever opened the oil filler cap and checked for oil sludge? Do you use regular gasoline? Greetings, André

Hi,
The distance to travel is 40 km twice a day.
So, a short distance is not the issue.
The engine oil is LL 5W30, and the vehicle is not being driven aggressively.
Oil sludge is also not visible in that way.

Next week, I'll start by having the oil pressure checked.

I haven't yet encountered a single PD motor where the oil pump was defective.
Let alone a TDI engine failing due to lack of oil pressure.
Does the oil pressure indicator light up red or yellow on the instrument cluster?

I have never heard of a situation where an oil pump is defective and a TDI engine doesn't have enough oil pressure.

It only rains occasionally.
If we measure the oil pressure while the engine is running, it's likely okay, otherwise the warning light would be on. I can't say for sure about the color right now, but I think it's red.

Wurstblinker wrote:

I have also never heard of a situation where an oil pump is defective and a TDI engine does not have sufficient oil pressure. It only rains occasionally. If we measure the oil pressure while the engine is running, it's definitely okay; otherwise, the warning symbol would be lit up. I can't say for sure about the color right now, but I think it's red.

No, the oil pressure warning light doesn't come on until the engine has been revved above 2000 RPM. Otherwise, at idle, the oil pressure can be 0.05 bar, and in that case, no warning lights will illuminate.

I have also never heard of a situation where an oil pump is defective and a TDI engine does not have sufficient oil pressure.

It only rains occasionally.

When does the lamp turn on? After you have properly accelerated the engine and then allowed it to coast to a stop?
Then it could be due to a problem with the oil pressure regulator (bypass). If this regulator is stuck, it can cause this effect. I've experienced this issue with gasoline engines before.

Okay, and most importantly: Measure the oil pressure as quickly as possible.

Best regards, Jochen.

It's quite possible that the warning light only comes on when the engine speed exceeds 2000 RPM! I haven't observed it closely because I rarely drive the car.

The strange thing is, after the change of battery, there were two weeks of peace. Now, this old clunker (we've had a lot of trouble with this car) is beeping almost constantly.

The oil pressure will be checked on Wednesday.

Regards,
Sausage blinkers.

As mentioned above. Please pay attention to whether the icon is yellow. Then the oil level sensor is probably broken.

Hi Steffarn,
It's red, and it also says 'low oil pressure.'

If the oil pressure test reveals an actual oil pressure that is too low, I will first perform an engine flush.

If the oil channels or the strainer in front of the oil pump are actually blocked, this method might potentially fix the problem.
Or a bearing has failed, preventing the build-up of oil pressure.
Accessing the oil pump requires a significant amount of work; according to Audi, it takes approximately 7 hours, as the front axle needs to be lowered to remove the oil pan.

Okay,
It was indeed the oil pressure switch. The oil pressure was measured and is okay.
I have no idea what the mechanic was working on first, sometimes he doesn't have the best ideas.

Anyway, things are calm again now, and we're curious to see what happens next!

Sure, here's the translation:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which translates to 'Sincerely' or 'Best regards' in English.