Also if you have erratic voltage on middle terminal, disconnect the wire connector and check resistance between middle and the third terminal on the sensor. Can can be off. When the air sensor plate is on the top, the resistance should be between 1 and 2K. Now gradually push the plate downward, the resistance should gradually increase. There should be no jumps greater than 4K. Otherwise, the pot needs replacement.

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Saumil S. Patel