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. During engine warm up, the HO2S1 should warm up, and its voltage output should vary between 150 mV and 850 mV. When the HO2S1 voltage varies, the engine will go into Closed Loop. This determines if the HO2S1 is operating properly.
3. This will determine if the sensor is malfunctioning or if the wiring or the ECM is the cause of the DTC P0134.
4. Use only a high impedance digital voltmeter (DVM) for this test. The test checks the continuity of the HO2S1 signal and the ground circuit; if the ground circuit is open, the ECM voltage on the circuit will be over 0.6 V (600 mV).
5. The replacement ECM must be reprogrammed.

   Refer to the latest Techline procedure for ECM reprogramming.