Intention Of Troubleshooting Procedure

Step 1-2
- Perform inspection of HO2S and A/F sensor signal related parts.
Step 3-7
- Perform inspection of each separate part.
Step 8-9
- Verify that the primary malfunction is resolved and there are no other malfunctions.

DTC P0421:00 PCM (SKYACTIV-G 2.5 - WITH CYLINDER DEACTIVATION) TROUBLESHOOTING DIAGNOSTIC PROCEDURE

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.
1		No	Retighten the HO2S, then go to Step 8. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)] .)
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 2.5 (WITH CYLINDER DEACTIVATION)] .) (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)] .)
2		No	Retighten the A/F sensor, then go to Step 8. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)] .)
3	PURPOSE: INSPECT INSTALLATION OF HO2S Inspect installation of HO2S. Is the HO2S installed securely?	Yes	Go to the next step.
3		No	Retighten the HO2S, then go to Step 8. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)] .)
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.
4		No	Retighten the A/F sensor, then go to Step 8. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)] .)
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.
5		No	Go to the next step.
6	PURPOSE: VERIFY IF OTHER DTCs ARE DISPLAYED Reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS. (See CLEARING DTC [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))] .) Implement the repeatability verification procedure. (See REPEATABILITY VERIFICATION PROCEDURE .) Perform the Pending Trouble Code Access Procedure and DTC Reading Procedure. (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))] .) Are any other PENDING CODEs and/or DTCs present?	Yes	Go to the applicable PENDING CODE or DTC inspection. (See DTC TABLE [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))] .) Go to the next step.
6		No	Go to the next step.
7	PURPOSE: VERIFY CATALYTIC CONVERTER (WU-TWC) MALFUNCTION Clear the DTC from the PCM memory using the M-MDS. (See CLEARING DTC [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))] .) Implement the repeatability verification procedure. (See REPEATABILITY VERIFICATION PROCEDURE .) Perform the Pending Trouble Code Access Procedure. (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))] .) Is the PENDING CODE for this DTC present?	Yes	Replace the exhaust manifold, then go to the next step. (See EXHAUST SYSTEM REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)] .)
7		No	DTC troubleshooting completed.
8	PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION Always reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS. (See CLEARING DTC [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))] .) Implement the repeatability verification procedure. (See REPEATABILITY VERIFICATION PROCEDURE .) Perform the Pending Trouble Code Access Procedure. (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))] .) Is the PENDING CODE for this DTC present?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)] .) Go to the next step.
8		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 2.5 (WITH CYLINDER DEACTIVATION))] .)
9		No	DTC troubleshooting completed.