Diagnostic Aids

An open fuse in the HO2S heater circuit may be caused by a short in the sensor heating element. The short may not be present until the sensor operates for a period of time. If no fault is present in the heater circuit, monitor the current of each heater with a scan tool to determine if one of the heater elements is the cause of the open fuse.

If the condition is intermittent, wiggle the related wiring harnesses and connectors, with the ignition/vehicle on or engine running, while monitoring the scan tool circuit status parameters for the component. The parameters will display if there is a condition with the circuit or a connection.