Thats is not the voltage you want on the center pin. You have measured this voltage with respect to battery ground right ? In other words, the red terminal of the meter was on the middle pin and the black terminal was grounded somewhere.

Find out what is the voltage between terminal 3 on the air sensor connector and ground. It should be close to 5V. If you dont get this, this is another big problem. Keep engine on for this test.

For this test, engine can be off. Check wire continuity for the air sensor wires from the sensor connector (terminals 2 and 3 only) to the ECU connector (17 and 18 respectively).

Also you want to check that the wires are not shorted to ground anywhere. Disconnect the connector from the air sensor. Check the resistance between terminal 3 (in the sensor connector) and battery ground. You should not get close to zero resistance. Check the same for terminal 2 in the sensor connector.

If you do find continuity, and dont find a short, then the problem is with the ECU, it is not sending 5V on its terminal 18. You may even be able to test this right at the ECU. Keep ignition on start position (car not running), and check if there is 5V on this terminal with respect to battery ground.

It seems like your wiring harness from the ECU may have more problems than initially thought. If there is one more harness problem, this is the one part you should replace as soon as possible.

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Saumil S. Patel