Oxygen Sensor: Testing and Inspection

Chart C-1F:

Oxygen Sensor Circuit:

CIRCUIT DESCRIPTION:

The generator charging circuit supplies battery voltage to the heater part of the oxygen sensor. The heater warms the O2 sensor to allow a varying voltage to be produced by the O2 sensor more rapidly instead of waiting for the O2 sensor to heat-up on its own.

The following test procedures are for the heater part of the oxygen sensor. No malfunction codes will be logged if the heater fails to function properly.

TEST DESCRIPTION: Numbers below refer to the circled numbers on the diagnostic chart.

1. This will verify that battery voltage is present for the heater.

2. This check will test the ground circuit to the heater.

3. This tests the heater element resistance.