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Home >> Mazda >> 2024 >> CX-90 Turbo Select >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 21 (On-Board Diagnostic - Pcm (VIN A) (2 Of 4)) >> DTC P0421-00: Catalytic Converter System (PYUL) >> Function Inspection Using M-MDS

Function Inspection Using M-MDS

WARNING: This page is about a different variant/trim than selected.
P0421: 00 (PCM (PYUL)) DIAGNOSTIC PROCEDURE

Step Inspection Results Action
1 PURPOSE: IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA 
  • Is the DTC P0421: 00 on freeze frame data?
 Yes Go to the next step.
No Go to the troubleshooting procedure for DTC on freeze frame data.
(See DTC TABLE [PCM (PYUL)] ).
2 PURPOSE: RECORD VEHICLE STATUS WHEN DTC WAS DETECTED TO UTILIZE WITH REPEATABILITY VERIFICATION 
  • Record the freeze frame data/snapshot data.
    NOTE:
    • Recording can be facilitated using the screen capture function of the PC.
 - Go to the next step.
3 PURPOSE: INSPECT FOR OTHER RELATED DTCs 
  • Perform the DTC inspection for the PCM. (See DTC INSPECTION .)
  • Are any other DTCs displayed?
 Yes Repair or replace the malfunctioning location according to the applicable DTC troubleshooting.
(See DTC TABLE [PCM (PYUL)] ).
Go to the next step.
No Go to the next step.
4 PURPOSE: VERIFY A/F SENSOR AND HO2S INPUT SIGNAL 
  • Start the engine and warm it up completely.
  • Access the following PCM PIDs using the M-MDS. (See PID/DATA MONITOR INSPECTION .)
    • A/F_SEN_CUR
    • HO2S_OUT_VOLT
  • Drive the vehicle under the following conditions.
    WARNING:
    • To prevent an accident, work with two people when the vehicle is being driven (one person drives vehicle, other person operates M-MDS).
    • Observe legal speed limits when driving the vehicle and perform the procedure in a location where safety can be assured.
    • After increasing the engine speed to 3, 000 rpm, decelerate using engine braking.
  • Is the displayed PID value as follows?
    • A/F_SEN_CUR: 0.25 mA or more
    • HO2S_OUT_VOLT: 0.3 V or less
 Yes Go to Troubleshooting Diagnostic Procedure to perform the procedure from Step 3.
No Go to the next step.
5 PURPOSE: VERIFY CONNECTOR CONNECTIONS 
  • Access the following PCM PIDs using the M-MDS. (See PID/DATA MONITOR INSPECTION .)
    • A/F_SEN_CUR
    • HO2S_OUT_VOLT
  • Does the PID value fluctuate when the following connectors are shaken?
    • A/F sensor
    • HO2S
    • PCM
 Yes Repair or replace the applicable wiring harness or connector parts.
Go to Troubleshooting Diagnostic Procedure to perform the repair completion verification 1.
No Go to Troubleshooting Diagnostic Procedure to perform the procedure from Step 1.
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