Oxygen Sensor: Testing and Inspection

Oxygen Sensor Schematic:

A faulty oxygen sensor will set code 32 in the on-board diagnostic system. Refer to the schematic diagram and test the sensor with the diagnostic chart.

Wire color code identification:

L: Blue
B: Black
Y: Yellow
G: Green
R: Red
W: White
Br: Brown
Lg: Light green
Gr: Gray

Oxygen Sensor Diagnostic Chart:

OXYGEN SENSOR DIAGNOSTIC CHART

Oxygen Sensor Testing:

CHECK ECU VOLTAGE AND OXYGEN SENSOR

1. With engine completely warmed up and idling, measure voltage between ECU connector (F121)4 and ground. Voltage should alternate between 0.3V and 0.6V.
2. Disconnect oxygen sensor and measure voltage between sensor connector (F5)1 and ground. Voltage should remain above .47 volts most of the time.

Oxygen Sensor Harness Testing:

CHECK ECU HARNESS

1. With ignition "OFF," disconnect ECU and oxygen sensor connector.
2. Measure resistance between ECU connector and oxygen sensor connector:

Connector & terminal: Resistance:
(F121)4-(F5)1 Below 1 Ohm

3. Connect ECU and oxygen sensor connectors.
4. Measure resistance between ECU connector and ground:

Connector & terminal: Resistance:
(F121)1-Ground Below 10 Ohms
(F121)2-Ground Below 10 Ohms