Where is the oil temp sensor?

[Cronenberged]

Im no longer getting oil temp readings, the needle doesn't even move off 120. I know the oil level is in the pan under the car, but does that also read the temperature?

[Tbonem3]

Yes iirc. I think there might be another sensor on the engine up higher (on filter housing, could just be pressure), but I think the data for the read out (low oil and temp) comes from below.

[cobra]

Somewhat related, but wasn't there some thing about how the oil temperature reading is 'fake' and based on coolant temperature? Or am I confusing it with something else?

[D-O]

When my gauge stopped working it was the sensor in the bottom of the pan.

[Cronenberged]

Tbonem3 yea RealOEM has that labeled but looks like its valve control for letting the oil flow.

cobra yoir guess is as good as mine

D-O Thank you, I'll order a new one.

If I just did my oil change 500 miles ago and I have an extractor is it safe to reuse the oil?

[Slideways]

Im no longer getting oil temp readings, the needle doesn't even move off 120. I know the oil level is in the pan under the car, but does that also read the temperature?

Yes. There will also be an error code for the oil level sensor in the DME and the yellow oil light will turn on during startup. It does not throw a check engine light.

[Altaran]

Somewhat related, but wasn't there some thing about how the oil temperature reading is 'fake' and based on coolant temperature? Or am I confusing it with something else?

It's calculated, not measured. I wouldn't call it fake, but it's not accurate at all.

The oil level sensor is what's called TÖNS (Thermischer ÖlNiveauSensor >> thermal oil level sensor)

It's essentially a heating element. That measures time in a heating cycle and a cool down cycle. Afaik heat cycle is for temp and cooling cycle is for level. It communicates values to the instrument cluster via PWM. The instrument cluster has the corresponding functions coded in to extrapolate the oil temp and level readings.

That's why all race converted cars are equipped with a separate oil temp sensor that has a conventional measurement method which is way more accurate.

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[cobra]

It's calculated, not measured. I wouldn't call it fake, but it's not accurate at all.

The oil level sensor is what's called TÖNS (Thermischer ÖlNiveauSensor >> thermal oil level sensor)

It's essentially a heating element. That measures time in a heating cycle and a cool down cycle. Afaik heat cycle is for temp and cooling cycle is for level. It communicates values to the instrument cluster via PWM. The instrument cluster has the corresponding functions coded in to extrapolate the oil temp and level readings.

That's why all race converted cars are equipped with a separate oil temp sensor that has a conventional measurement method which is way more accurate.

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Fascinating!
Thanks for sharing.

[heinzboehmer]

Straight from TIS:


TBH, oil level/temp data from the DME has been accurate enough for me. Have not seen a need for a separate sensor.

Altaran do you have data comparing the readouts from the stock sensor and the aftermarket one you installed?

[davidinnyc]

I just replaced the oil temperature sensor on the bottom of the pan, same symptoms as you (needle won't move above 120 or would randomly move up then back down quickly). Problem solved with a new unit.

[Altaran]

Altaran do you have data comparing the readouts from the stock sensor and the aftermarket one you installed?

I don't. Unfortunately my aim dash cannot read PWM signals plus the conversion between PWM values and temperature is not openly available.
The only way for me to make it work is either use a raspberry pi with custom programming or remove the PCB from the original cluster and reconnect it to the background somehow. Both a lot of effort to get data which is not completely accurate.

I also measure temperature as it goes into the engine, which makes more sense to me to see that it's within proper viscosity range as it goes in. I was running on the track yesterday, at ambient temperatures of 20°C my oil temp does not exceed 87°C. By letting it warm up for a couple of minutes, I can have it surpass 75°C so it's within proper temp. I do run a DO88 oil cooler and an oil thermostat delete, so I was happy to see these things work.

The sensor I use is a Bosch 280130026. It's reasonably priced, the sensor resistance curve is available, and has a M12x1,5 thread so it fits into the factory oil filter housing bore. (One of the two where the oil pressure switch is located on a factory engine)

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[heinzboehmer]

I don't. Unfortunately my aim dash cannot read PWM signals plus the conversion between PWM values and temperature is not openly available.
The only way for me to make it work is either use a raspberry pi with custom programming or remove the PCB from the original cluster and reconnect it to the background somehow. Both a lot of effort to get data which is not completely accurate.

I also measure temperature as it goes into the engine, which makes more sense to me to see that it's within proper viscosity range as it goes in. I was running on the track yesterday, at ambient temperatures of 20°C my oil temp does not exceed 87°C. By letting it warm up for a couple of minutes, I can have it surpass 75°C so it's within proper temp. I do run a DO88 oil cooler and an oil thermostat delete, so I was happy to see these things work.

The sensor I use is a Bosch 280130026. It's reasonably priced, the sensor resistance curve is available, and has a M12x1,5 thread so it fits into the factory oil filter housing bore. (One of the two where the oil pressure switch is located on a factory engine)

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Right, I forgot your car doesn't have a stock cluster anymore.

[jayjaya29]

If you wanted to replace the factory oil level/temp unit with an aftermarket one, this would work:

https://www.moreheadspeedworks.com/product/msw-bmw-oil-temp-sensor-flange-m5x-s54-e36-e46-z3-z4/

[Altaran]

Right, I forgot your car doesn't have a stock cluster anymore.

We would need someone with a stock cluster and an extra display that accepts sensor, such as AK motion, to connect a proper sensor and compare the readings.
It would only work while the engine is cold. Once oil temp goes up and flow is directed through the oil cooler, measurements at the oil filter housing will show cooler than at the sump.

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[bigjae46]

The gauge in the cluster is off but the actual reading from the ECU is accurate.

I ran an aftermarket oil temp gauge with the sender that replaced the oil pan plug. The aftermarket gauge read pretty much the same as the ECU data on my AiM Solo...within +/- 5 degrees every time I checked it. When I pull oil temp data the ECU is recording some significant changes during a lap, up to 30 degrees in some cases. I'd expect the oil temp needle in the OE gauge to move a lot more but I've never observed much movement. It's a track car, so I usually only check the gauges when I'm on a straight.

I deleted the aftermarket gauge since it was mostly redundant with the AiM solo DL. But I'd be confident that the OE gauge would tell me when the oil temps are getting hot and I should back off. I just would rather have a little more info to tell me when things are starting to get hot so I can back off a little earlier to reduce the likelihood of an issue.

Here is a video with oil temp data. The data is from the AiM Solo D-CAN connection so its from the ECU. You can kind of see the gauge in the cluster