[BR3W CITY]

For fun, knock sensors technically don't measure spark knock. They measure all knock. You can ping you motor with a hammer and watch it log on the knock sensors. Burst knock vs spark knock vs mechanical knock.

Flex fuel sensor, sits in line with the fuel feed, measures ethanol content of fuel by measuring the capacitance using an a/c current across the fuel stream.

ISS/VSS/OSS - the various input and output speed sensors. On LS motors they don't really read speed, they read reluctance (output speed may differ from input speed), and use that value with the tire size value in the PCM to calculate speed. The ISS/OSS can differ to measure loss/slip. This is also why you'll see them sometimes compare these values to wheel speed (ABS ring speed) for traction control.

Probably best to define WHICH gen we're talking about here. Sensor locations and ways they function change GenIII-GenV.