Since my beloved 1995 940 does not have a reliable OBD port to diagnose with, I assume it is theoretically possible to get sensor readings by measuring the voltage going through the EZK and ECU. Has anybody been able to reliably diagnose sensors by probing it? I've seen pinouts, but am not yet sure how to do it.

I apparently have a Bosch LH 2.4 on a B230FK. I am trying to troubleshoot a check engine light and fuel mix problem as soon as the car is in warm operation temperature. I am trying to check if my sensors are sending the correct readings to the computer, without splicing up their cables.