Confirmation Engine Racing Pattern
Connect the hand-held tester to the DLC3, or connect the probe of the oscilloscope between terminals OXL1, OXL2, OXR1, OXR2 and E1 of the ECM connectors. Start the engine and warm it up with all the accessories switched OFF until engine coolant temperature is stable. Race the engine at 2500-3000 RPM for about 3 minutes. After confirming that the waveform of the heated oxygen sensor (bank 1, 2 sensor 1 (OXL1, OXR1), oscillate around .5 volts during feedback to the ECM, check the waveform of the heated oxygen sensor (bank 1, 2 sensor 2 (OXL2, OXR2). See Fig 1.
If there is a malfunction in the system, the waveform of the heated oxygen sensor (bank 1, 2 sensor 2 (OXL2, OXR2) is almost the same as that of the heated oxygen sensor (bank 1, 2 sensor 1 (OXL1, OXR1) on the left. There are some cases where, even though a malfunction exists, the MIL may either light up or not light up. See Fig 2.