I had recently serviced my A4 via Audi, and all previous services were at the correct intervals and by main dealer also. When driving a month later, and a few thousand miles more the MIN error occurred on the dashboard. I pulled up checked the oil level- which was max, started the car again and the error has vanished. About 10miles, 20mins later the MIN error occurred again in which I checked again yet the level again was still max.
Audi's have a built-in system, when you open the bonnet the dash is reset, hence the error vanishing. But whilst you are driving the system continuously checks itself therefore bringing up the error again if the fault is still present.
The error is: A yellow oil symbol with the words MIN at the bottom.
This is NOT related to the OIL pressure sensor, and is located at the bottom of the car next to the oil sump plug.
After reading the forums and checking the sensor for any obvious signs for problems I decided to get the sensor replaced. My first instinct were to see is there are any after-market equivalents as I did not want to spend a lot on a sensor that tells me the same as a dipstick would!
The part number of the part I required for my car was: 06E 907 660
Hella equiv: 6PR 008 079-05
Audi charge £87, where as I was able to locate a part from an OEM alternative manufacturer (HAMBURG-TECHNIC) for £50.
FROM MY EXPERIENCE USE AUDI PARTS and this is why:
In order to replace the part you will need to drain the oil (ideally change part when an oil service is due) - you can try removing the sensor without drain but will cause a large oil mess.
When fitting the HT part all seemed well until driving a few miles down the road, the following error occurred: yellow oil symbol with SENSOR
This indicates the sensor is not being read, hence having to replace again (that includes draining the oil once again)
This time I opted for the original part from Audi, which worked correctly, and hence no more errors being produced.
(I was able to reuse my oil because the oil filter was new - I would recommend using OE parts due to the 2 year warranty and guaranteed compatibility, no need to do the job twice!)