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Home >> Lexus >> 2004 >> IS 300 Base, Standard >> Repair and Diagnosis >> Engine Performance >> Engine Control System - Diagnosis >> Circuit Inspection >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1), DTC P0430: Catalyst System Efficiency Below Threshold (Bank 2) >> Confirmation Engine Racing Pattern

Confirmation Engine Racing Pattern

Fig 1: Confirmation Engine Racing Pattern
G01496345Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  1. Connect the hand-held tester to the DLC3, or connect the probe of the oscilloscope between terminals OX1A, OX1B, OX2A, OX2B and E1 of ECM connectors
  2. Start the engine and warm it up with all the accessories switched OFF until engine coolant temperature is stable
  3. Race the engine at 2,500-3,000 RPM for about 3 min.
  4. After confirming that the waveform of the heated oxygen sensor (bank 1,2 sensor 1 (OX1A, OX2A)), oscillate around .5V during feedback to the ECM, check the waveform of the heated oxygen sensor (bank 1,2 sensor 2 (OX1B, OX2B)).

HINT:

If there is a malfunction in the system, the waveform of the heated oxygen sensor (bank 1,2 sensor 2 (OX1B, OX2B0)) is almost the same as that of the heated oxygen sensor (bank 1, 2 sensor 1 (OX1A, OX2A)) on the left.

There are some cases were, even though a malfunction exists, the MIL may either light up or not light up.

Fig 2: Identifying OX Signal Waveform
G01496346Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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