I am pondering the idea of retrofitting an EGT sensor to my ME7.9.10 ECU (not for engine control, but simply to log EGT directly from the ECU instead of additional devices, in my case Zeitronix Zt-2). It seems from the documentation that the ECU is EGT ready (EGT connections are named and marked as unused), just not sure which kind of sensor it would use. I checked the connections on the ECU, the ECU connector pin described as EGT signal is connected to ADC input of the CPU, and with a bias resistor of 1k to +5V. To me it indicates that this should be a typical NTC of an appropriate range. The closest that would match what I would expect are the c-type EGT sensors from this video:

https://www.youtube.com/watch?v=sSwoaQ-ro0U

Looking at the resistance values, this would sensibly measure temperatures upwards of ~300 degrees C. These sensors (VW10X-CWE) are listed exclusively for TDI engines, and hence my total puzzlement if they would at all be any good. If they would, I also wonder about responsiveness / heat sinking issues...

I verified that the ECU pin is read and I get sensible values when playing with a potentiometer on the pin, there is even an CDATS flag in the ECU code, it's read and copied to a RAM flag, but then nothing happens to it, nor is the value read from ADC utilised in any way (but bit masked to be ready for use).

Any feedback is appreciated.

Thanks for the tip! I came across something of this sort, only did not pay too much attention to it, I will look into it more. In my particular case this probably brings new problems - additional cabling (what I want to avoid in the first place, I do have a working Zeitronix with EGT input), I have only one linear 0-5V input available on the ECU which I wanted for something else (AFR input for the same reason as initially stated), and as far as my poor electrics knowledge tells me, I cannot really plug in 0-5V into NTC ready pin that has a bias resistor. Nevertheless, the device seems cool and cheap enough to consider this way.