I agree however, by using a simple measurement at the O2 connection you are mixing voltage output from the O2 sensor and the bias voltage added by the FI system. The typical bias voltage (if present) is .45 volts ie if the sensor is removed you will still get .45 across the connection. The ECU, obviously aware of this bias voltage will logically subtract it out and conclude that the O2 sensor itself is not adding anything to the equation ie is producing zero volts and report it bad - code 2.

In my previous postings, I focused on what voltage is produced by the O2 sensor itself (which is what the ECU is reporting) and not what voltage may or may not be present at the connection.

But to backup to what I view as a simple trouble shooting step, if the engine is firing and the exhaust manifold has reach normal temps and the ECU is reporting that the O2 sensor is bad, then taking advantage of the fact that a DIABLO has two O2 sensors by simply unscrewing them and flipping them is 15 minutes of work to either confirm or discount the sensor being bad and requires nothing more than a wrench.

My D Roadster had a bad O2 sensor but worse it was intermittent. Flipping sensors was a very cheap and quick way to confirm the part failure. A failed O2 sensor on a Diablo (especially older ones) is not a unique problem.

-mick