Patent ID: 7090806

Claim:
An oxygen sensor analyzer for use in testing the performance of an oxygen sensor comprising a portion of a vehicle emission system having an on-board computer, the oxygen sensor analyzer comprising: (a) an electronic circuit having an oxygen sensor input for receiving an oxygen sensor signal from the oxygen sensor with the oxygen sensor disconnected from the on-board computer, a simulate output for connection to the on-board computer in place of the oxygen sensor, and logic means operative for driving the simulate output in: (i) a closed-loop mode wherein the simulate output directly follows the oxygen sensor input; and (ii) a simulate mode wherein the simulate output, being isolated from the oxygen sensor input, is driven in an arbitrary manner for forcing the engine to run one or both of lean by driving the simulate output to simulate a rich indication from the oxygen sensor, and rich by driving the simulate output to simulate a lean indication from the oxygen sensor; and a display for indicating the oxygen sensor signal.