I have a 2001 1.8T VW New Beetle. My coolant light always comes even after long periods of driving. I refill it with a little water and it goes off, but then goes on after driving it for a bit. It’s never gone off this much before.. is it just a faulty gauge? Also, my low oil pressure light always comes on too, but only when I’m slowing down and going downhill. These lights have been going on for a couple months and I was told if I really did have low oil pressure my car already would have broken down and I would have noticed it by the way my car drove. I also hit a big rock before my low oil pressure light came on, would that have anything to do with it? I do regular oil changes every 3k miles with Mobile1 5W-30 for high mileage (my beetle is at about 128k). The light still came on after doing an oil change. I don’t know where the sensor would be and if this is a serious problem and if I should be worried or not?
If this is occurring more often, the leak is getting worse.
It is important you find this for two reasons. 1) It could be a head gasket leaking, if this gasket continues to fail, you could end up with water getting into the cylinders and/or oil, at which time you will be doing a tear down, and 2) whatever the leak, it it were to fail severely at a high speed, the damage from the overheating may be so extreme before you can get it stopped that the damage will be done, and again you will be doing a tear down or engine replacement. To say nothing of the impending damage to the turbo. Also, if all you are adding each time is water, your system may be full but you will not have running temperature protection from the thinned down mixture.
As regards the oil pressure light issue, slowing on a downhill, is probably sloshing contaminants into the oil pick-up screen for the oil pump, or away from the pick-up. I don't know how it is positioned. Your oil pump may also be bad and be the cause of this. Again this is an issue which needs to be addressed as the Turbo relies on oil for cooling. Also you will greatly enhance cold start oil flow by going to a 0w oil and slightly improve oil pressure with the use of a w40 oil. I suggest Mobil 1 0w40 (VW Certfied).
I have serious doubts the sensors are bad in either one of your issues.
Coolant temp sensor will set off both lights. On mine the coolant light stayed blue, and the oil pressure light would flash on and off, plus that annoying warning beep. Changed the sensor (1/2 hour job at the most) no more lights.
The oil pressure light snould NOT come on with the low coolant light. The two are serviced by separate sensors. If this happens it could be caused by the oil possibly already breaking down and then under increased temperature thinning even more causing a drop in pressure or by a wiring issue. In your case, fixing the one resolving the other would indicate a false signal being sent to the oil pressure light by the ECM because of the bad coolant level sensor. Strange but possible; under normal circumstances, an indication of low coolant level (with a properly functioning sensor) will not trigger a low oil pressure warning light.
MORAV