# A new and useful observation of mine re: low oil pressure light blinking



## hakershermarkt (Oct 31, 2009)

For the past couple of years, I've noticed that every spring my low oil pressure light would come on when the weather would start to warm up. 

I went through all of the checks, and it came down to a faulty low oil pressure switch every time. I thought it to be peculiar that a low oil pressure sensor would have a life span that you could almost calculate by the day. 

I did some trial and error testing, and I came to this conclusion:

We've all seen (or at least heard of) this "goop" before:










Often it's been described as the result of "condensation build up" in your engine from short trips or what have you. 

Well, this stuff doesn't necessarily have a critical mass. If you take short trips in a cold climate through the winter on a daily basis, or god forbid if you have a headgasket issue or some other way that coolant is getting into your oil, this stuff will continue to build up at the top of your engine.

Eventually, it will start to run down the sides. If you have a mk3 ABA 2.0l, (and this could be the case for other engines as well), eventually this goop will run down in front of the low oil pressure sensor and block it.

This goop has a much different viscosity than oil (regardless of weight), and in effect it will block your low pressure sensor from reading the correct oil pressure and your light will come on.

The oil pressure sensor looks something like this (though, in this image, this is the high pressure sensor):










Inside of it is essentially just a spring that opens up under pressure. When it opens, the connection becomes ungrounded and the little blinking light goes out. When it closes, and the engine is still running / ignition still engaged, it will blink. 

Essentially the goop insulates this mechanism from opening, keeping the sensor closed, and your light will begin blinking. You will probably s**t yourself shortly thereafter, just to learn that the culprit is the notorious volkswagen mayonaise.

For a more detailed (and helpful) explanation of the low/high oil pressure warning system, check out Vince Waldon's page here:

http://vincewaldon.com/index.php?option=com_content&task=view&id=40&Itemid=28

I hope that this helps some people in their quest to figure out what is going on with their oil pressure warning system.


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