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Home >> Mazda >> 2017 >> CX-5 Grand Select, FWD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> On-Board Diagnostic - Engine Control System (2 Of 5) >> DTC P0421-00: Catalytic Converter System >> Troubleshooting Diagnostic Procedure >> Intention of troubleshooting procedure

Intention of troubleshooting procedure

FUNCTION INSPECTION DESCRIPTION

STEP INSPECTION RESULTS ACTION
1 PURPOSE: INSPECT INSTALLATION OF HO2S
  • Inspect installation of HO2S.
  • Is the HO2S installed securely?
Yes Go to the next step.
No Retighten the HO2S, then go to Step 8.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
2 PURPOSE: INSPECT INSTALLATION OF A/F SENSOR
  • Inspect installation of A/F sensor.
  • Is the A/F sensor installed securely?
Yes Replace the A/F sensor and/or HO2S, then go to Step 8.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Retighten the A/F sensor, then go to Step 8.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
3 PURPOSE: INSPECT INSTALLATION OF HO2S
  • Inspect installation of HO2S.
  • Is the HO2S installed securely?
Yes Go to the next step.
No Retighten the HO2S, then go to Step 8.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
4 PURPOSE: INSPECT INSTALLATION OF A/F SENSOR
  • Inspect installation of A/F sensor.
  • Is the A/F sensor installed securely?
Yes Go to the next step.
No Retighten the A/F sensor, then go to Step 8.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
5 PURPOSE: INSPECT EXHAUST SYSTEM FOR LEAKAGE
  • Visually inspect for exhaust gas leakage from the exhaust system.
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results, then go to Step 8.
No Go to the next step.
6 PURPOSE: VERIFY IF OTHER DTCs ARE DISPLAYED Yes Go to the applicable PENDING CODE or DTC inspection.
(See DTC TABLE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .)
Go to the next step.
No Go to the next step.
7 PURPOSE: VERIFY CATALYTIC CONVERTER (WU-TWC) MALFUNCTION Yes Replace the exhaust manifold, then go to the next step.
(See EXHAUST SYSTEM REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No DTC troubleshooting completed.
8 PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION Yes Repeat the inspection from Step 1.
Go to the next step.
No Go to the next step.
9 PURPOSE: VERIFY IF THERE IS ANY OTHER MALFUNCTION
  • Is any other DTC or pending code stored?
Yes Go to the applicable DTC inspection.
(See DTC TABLE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .)
No DTC troubleshooting completed.