The oil gauge on my 1990 XJ-6 (XJ-40) doesn't register anything. I know oil pressure is good. I was told when I bought the car that the wire had broken off the sensor. I've been trying to locate it, and think I've found it, but the wire is still connected. Looking at my photo, does this look like the oil sensor?

It's hard enough to see this thing, let alone replace it. Is it a difficult job to do?

 

Yep that's it. You'll need a 3/4" crowsfoot to get it off.

Larry

 

Just wondering... How can I test if the sensor is bad? If I were to disconnect the wire, would the gauge do anything, or stay at zero? Could I connect the wire to the + battery terminal to see if the gauge moves, or will that blow the gauge?

 

You could try cleaning the contact to see if that makes any difference but IME these sensors are a very common failure item and most of us just replace them.
I wouldn't advise directly powering the gauge with 12v because I don't know what the result would be -however, hooking the wire up to a variable resistor like a grounded volume control might work. I don't know for sure, just guessing.

Because of being mounted horizontally these things are always half full of oil - oil that never gets drained during oil changes. Over time, I believe this causes residue to build up internally eventually blocking or at least partially restricting the small aperture.
Some members have successfully cleaned the sensor with brake cleaner but because of the work involved in removing it, replacement may be the best option.

This same sensor has been used in Jaguar cars since the 1950's where it was always mounted vertically. Interestingly, the high failure rate of the sensor only began with the XJ40 when the designers opted for the horizontal installation.

Larry

 

You GROUND the sensor wire to send the gauge to FULL SCALE as a test,

 

Makes much more sense that way. Thanks! Now I have something I can try out while I'm waiting for my parts to show up.