[Georgew221]

Yes, faulty temperature sensor, really common fault on the JTS engines. Try cleaning the contacts that supply the car with the temperature signal (sensor wiring comes out of the sump), as oil tends to wick through the cables into the connector.

If this doesn't work you'll have to remove the sump, which can be a pain in the ass if you've got a 3.2, or I've made an aftermarket solution:

Alfa Romeo 939 Series Oil Temperature Sensor - WorkingDesign

working-design.co.uk

Feel free to ask questions if you have any.

 

[Georgew221]

Forgive my ignorance, or call me a noob lol, but where exactly are the contacts?

You have to take the unplug the connector going into the sump, there's a yellow security tab which stops it rattling off, and then you need to lift the locking latch over the tab.

After that spray it with a ton of contact cleaner, when I did this mine came out jet-black because of how much oil had wicked!

 

[Georgew221]

My oil level gauge doesn’t even show on the display anymore but 10 years ago when it was working, it would randomly tell lies so these days I just rely on the dip stick. The oil temperature gauge I think is associated with this and on mine, it works but only when it feels like it.

Yeah, the two functions are baked into one part. There's elements on a PCB inside the sump which can break over time with the heating/cooling of the engine oil; same goes for the temperature sensor. Mine wound me up so much that I ended up making the replacement above 😂

 

[Georgew221]

So where does your replacement sensor go if the original part stays put where it is in the sump? I could imagine that maybe something bolted onto the sump wouldn’t be too far away from the oil inside it and that'd probably do the trick.

Rethreaded sump plugs with new temperature senders installed, although needs some conversion for the car to read the correct values to/from the new temperature sender

 

[Georgew221]

Got me thinking of alternate ways of electronically measuring the oil level. I could imagine being able to detect the fluid level in a milk bottle quite accurately from the sound made when it was tapped but I’m not sure if tapping a sump would give a similar effect. In theory it’s doable I suppose.

I've been trying to think of a method of doing it accurately but long-lasting. If the sump plug was vertical I could remake the PCB, but I haven't looked too much into it.