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WARM-UP THREE-WAY CATALYTIC CONVERTER (WU-TWC) INSPECTION (EUROPEAN (L.H.D.) SPECS.) [AJ]

BME011620500202

  Note

  • Make sure that no HO2S DTCs have been detected. If detected, this inspection is not applicable for TWC inspection.

1. Connect the WDS or equivalent and monitor PIDs as following.

  • Monitor the left WU-TWC using O2S21 PID for upstream HO2S and O2S22 PID for downstream HO2S.
  • Monitor the right WU-TWC using O2S11 PID for upstream HO2S and O2S12 PID for downstream HO2S.

2. Begin to monitor the appropriate PIDs.

3. Drive the vehicle for 10 min at 65-96 km/h {40-60 mph} to allow the front catalytic converter to reach operating temperature.

4. Stop the vehicle and leave it in a safe place.

5. Let the engine idle.

6. Record PIDs for 1 min.

7. Select the appropriate PIDs and read the graph.

8. Count the number of times (inversions) that the upstream HO2S graph line actually crosses the 0.5 V line.

9. Count the number of times (inversions) that the downstream HO2S graph line actually crosses the 0.5 V line.

  Note

  • Do not count the number of peaks. Refer to the graph.

10. Using the following equation, calculate the value of ratio.

Equation

  RATIO = Upstream HO2S inversion downstream HO2S inversion

  • If the ratio is 2 or more or there is no downstream HO2S inversion, the WU-TWC is functioning properly.
  • If the ratio is less than 2, the WU-TWC is not functioning properly. Replace the WU-TWC.

Upstream HO2S graph line example

Downstream HO2S graph line example 1

Equation

  RATIO = 26 inversions (upstream HO2S inversions) 7 inversions (downstream HO2S inversions) = 3.7 (good WU-TWC)

Downstream HO2S graph line example 2

Downstream HO2S graph line example 3

Equation

  RATIO = 26 inversions (upstream HO2S inversions) 19 inversions (downstream HO2S inversions) = 1.4 (deteriorated WU-TWC)