Oxygen Sensor 2, Left Side

Trouble Code 37, Left Side Oxygen Sensor Diagnosis:

Trouble Code 37, Left Side Oxygen Sensor Circuit Diagram:

1. CHECK INPUT SIGNAL FOR ECU
a. Connect voltmeter between terminal #5 of the ECU B59 connector and ground.
b. Start engine and idle.
c. Observe voltmeter.

Should be between 0.1 and 1.0 volt

Oxygen Sensor Connector Identification:

2. CHECK OXYGEN SENSOR
a. With engine idling, disconnect oxygen sensor electrical connector.
b. Measure voltage between body ground and oxygen sensor connector terminal #4 (sensor side).

Should be between 0.1 and 1.0 volt


3. CHECK HARNESS CONNECTOR BETWEEN ECU AND OXYGEN SENSOR
a. Turn ignition OFF.
b. Disconnect ECU and oxygen sensor electrical connectors.
c. Check resistance of wire between ECU connector B59 terminal #5 and terminal #4 of the oxygen sensor connector.

Should be approx. 0 ohms

d. Leaving one probe still connected to the oxygen sensor connector terminal #4, connect other probe to body ground.
e. Observe ohm reading.

Should be greater than 1 Meg ohm

4. CHECK HARNESS CONNECTOR BETWEEN OXYGEN SENSOR AND MAIN RELAY
a. Disconnect main relay connector under drivers side of the dash board.
b. Check resistance between oxygen sensor terminal #1 and main relay terminal #2.

Should be approx. 0 ohms

c. Check resistance between oxygen sensor harness terminal #2 and main relay terminal #4.

Should be approx. 0 ohms

5. CHECK POWER SUPPLY CIRCUIT OF MAIN RELAY
a. Turn ignition switch ON.
b. Measure voltage between main relay harness terminals #2 and #4 and body ground.

Should be greater than 10 volts