G 2500 3/4 Ton Van V8-350 5.7L VIN K TBI (1995)
Oxygen Sensor: Testing and Inspection
Diagnostic Trouble Code (DTC) 13 indicates an open in the oxygen sensor circuit, DTC 44 indicates a shorted oxygen sensor circuit. DTC 45 indicates a
high voltage in the oxygen sensor circuit. If a DTC is set, the engine will always run in the "Open Loop" mode. On heated oxygen sensors the value will
drop lower towards 0 as the sensor heater inside the sensor warms up. Tests are located in System Diagnosis. See: Powertrain Management/Computers
and Control Systems/Testing and Inspection
SCAN TOOL USAGE
Normal scan voltage varies between 100 mV to 999 mV (0.1 and 1.0 volt) while in "Closed Loop." DTC 13 sets in one minute if voltage remains
between 0.35 and 0.55 volt, but the system will go "Open Loop" in about 15 seconds.
Using the scan, observe the long term fuel trim values at different RPM and air flow conditions to determine when DTC 44 or DTC 45 may have
been set. If the condition for DTC 44 exists, the long term fuel trim values will be around 150. If the condition for DTC 45 exists, the long term
fuel trim values will be around 115.
HARNESS DAMAGE
If the heated oxygen sensor pigtail wiring, connector or terminal is damaged, the entire oxygen sensor assembly must be replaced. Do not attempt
to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean
air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result
in the obstruction of the air reference and degraded oxygen sensor performance.
