99 300tdi oil warning light comes on

**Erik BM** · 29th October 2008, 09:37 PM

Hi All,
I have just replaced the head on my 300 tdi series 1 and now, much to my disgust, the oil warning light comes on when it drops down to idle speed. It has only recently done it and I have been driving it for 3 weeks since the head was done (by me).

I have checked that it has oil - which it does. I changed the oil and oil filter when I did the head. The oil warning light goes off when I rev it. It has only done 165K so it shouldn't be worn yet. Where do i start checking?

Thanks, Erik

**justinc** · 29th October 2008, 09:51 PM

Erik,

Don't worry, there are several possibilities here. 1 is that the switch has failed. Take a close look at it, if it is still the original one, they are originally opaque and if it is now black/ dark grey, or is actually leaking oil, then it has failed. They fill up with oil and create a circuit to earth when this happens, switching on the dash warning light.
2ndly, they can be damaged by water ingress due to high pressure cleaning, the moisture can get into the outer housing and again, create a circuit to earth.

This symptom is typical of these failures.

And take heart that if the light really was accurate, then there would be very little bearing material left by now

JC

**Erik BM** · 30th October 2008, 06:09 AM

Thanks JC,

I have indeed taken heart from your answer.

BTW, where is the switch?

Regards, Erik

**justinc** · 30th October 2008, 06:12 AM

Originally Posted by Erik BM

Thanks JC,

I have indeed taken heart from your answer.

BTW, where is the switch?

Regards, Erik

Just above the oil filter, drivers side of engine. It is just a small screw in switch with a single terminal , a flat pin connection.

JC

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