Chart 14 Oxygen Sensor Test

1. Start engine and enter diagnostics. Display Data Parameters .0.4.

2. Operate engine at fast idle until coolant temperature reaches 85°C or greater.

3. Display Engine Data Parameter .0.7 and note O2 sensor values at fast idle.

VOLTAGE SWINGS BELOW 30 AND ABOVE 60:
While operating engine at fast idle, observe Open/Closed loop status light above "OFF" button on ECC control head.
^ If the light is ON, O2 sensor if good.
^ If the light is OFF, replace O2 sensor.

VOLTAGE REMAINS BELOW 30 AND ABOVE 60 FOR EXTENDED PERIODS OF TIME:
Check for leaded or contaminated fuel (i.e. tampered fuel neck)
Check for contaminated O2 sensor (silicone sealer contamination)
Check for a faulty O2 sensor connection or a faulty sensor.

NO VOLTAGE VARIATION:
Replace O2 sensor.
Check for a faulty O2 sensor connection or a faulty sensor.