Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
2. This step determines if DTC P0135 is the result of a hard failure or an intermittent condition. With the ignition ON, engine OFF, the HO2S1 voltage displayed on the scan tool should change within several minutes toward 0 or 1 V, indicating that the heater is working properly.
3. Probing terminal 1 of the HO2S1 connector verifies if voltage is available to the HO2S1 heater.
4. If voltage is available at the connector, than it becomes a good voltage source to check for a ground at terminal 4.
5. Determines if voltage is not available at the HO2S1 due to an open in the HO2S1 fuse or open ignition feed circuit. If the fuse is open, determine if it was due to a short in the ignition feed circuit before replacing the fuse.