AJ Model

WARNING: This page is about a different car, the 2005 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

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

Connect the WDS or equivalent and monitor PIDs as following.
- Monitor the TWC using O2S11^*1 , O2S21^*2 PID for upstream HO2S and O2S12^*1 , O2S22^*2 PID for downstream HO2S.
*1: Right bank

*2: Left bank
Monitor the appropriate PIDs.
Drive the vehicle for 10 min at 65-96 km/h {40-60 mph} to allow the front catalytic converter to reach operating temperature.
Stop the vehicle and leave it in a safe place.
Idle the engine.
Record PIDs for 1 min.
Select the appropriate PIDs and read the graph.
Count the number of times (inversions) that the upstream HO2S graph line actually crosses the 0.5 V line.
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 Fig 1 .
Fig 1: Example Of HO2S Downstream Inversions
Courtesy of MAZDA MOTORS CORP.
Using the following equation, calculate the value of ratio.
Equation

RATIO = Upstream HO2S inversion downstream HO2S inversion
- If the ratio is 1.1 or more or there is no downstream HO2S inversion, the WU-TWC is functioning properly.
- If the ratio is less than 1.1 the WU-TWC is not functioning properly. Replace the WU-TWC.