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Porsche 996/997 oil level Sensor

Practical Motorsport Wiring - Professional Level

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Has anyone had any dealings with these oil level sensors? These are found on 996/997 Road and racecars. Sensor p/n is:9966061400 Porsche motorsport sells a oil level display unit that's meant for mechanics to read oil level from outside the car. These are £2500.

I want to retain this sensor in a customer 997, its running a life racing ecu and a cosworth Icd ultra dash. I would like to use the same logic porsche do for measuring oil level and certain temps etc. What I'm struggling with is how this works. I also believe I've read somewhere this is an oil temp sensor too.

This sensor is just a 2 pin device. Across the pins I'm only getting a resistance of 20 ohms, this figure doesn't change at any oil level(have sat this in a jug of oil).

I was wondering whether it'll need a pull up to 5v on one of the pins, but then again, I should see some resistance change under differing oil levels.

Appreciate any help if anyone has had an run ins with these sensors.

Thanks

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Hello, it might be an electrothermic sensor.

Basically, it is just a wire, the ecu heats the wire using an electrical pulse, after that it measures the resistance which changes by heating that resulated from the electrical pulse, and cooling from the oil, the lower the oil level the lower the cooling rate.

One way to confirm is to measure the resistance while putting it in oils with different temperatures, water might work too.

With only two terminals, I'd usually consider it to be an on-off switch, with a definite step between which would show up by turning it upside down vs correct orientation.

However, there are several different designs coming up and there are other ways it could be working. It may work like a fuel level sender which uses a float which changes the capacitance (IIRC) of the circuit, or it may use some other property, between the terminals. But some similar, two terminal, senders use the body as a ground and two different sensor levels for 3 different rages of the fluid, eg, low, normal, high. There is also a design that uses one side for low level and the other for temperature.

It might help narrow things down if you check the terminal to body resistances or, if you have a DMM that can do it, the capacitance between the terminals and a terminal and body.

If you can get hold of the wiring diagram for the vehicle, or another that uses the same sender, it should help a lot.

Rather than buying the Porsche tool, check out the OBD2 tools that are commercially available - some should work not only on the Porsche, but many other vehicles and their electronics/management systems. What's on offer can be confusing, as many seem to be offering the same things but have different model numbers, so take your time to ensure they do what you expect and want before purchase.

Some of the Oil Level sensors that I have dealt with also had a minimum temperature of the oil that they where in. This had to be exceeded before they would output a signal.

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