DTC P0421:00 [SKYACTIV-G 2.0, SKYACTIV-G 2.5]

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Details On DTCs

DESCRIPTION

Catalytic converter system
DETECTION CONDITION
Determination conditions
•  The PCM detects that the HO2S output fluctuates from lean to rich in a short amount of time at specified times continuously after recovery from fuel cut control.
Preconditions
•  Catalytic converter (WU-TWC) estimated temperature: above 400 °C {752 °F} (MTX)/above 380 °C {716 °F} (ATX)*1
•  HO2S estimated temperature: above 450 °C {842 °F}
•  The following DTCs are not detected
―  Misfire: P0300:00, P0301:00, P0302:00, P0303:00, P0304:00
―  Fuel injection correction: P0171:00, P0172:00, P2096:00, P2097:00
―  A/F sensor: P0130:00, P0131:00, P0132:00, P0133:00, P0134:00, P064D:00, P2237:00, P2243:00, P2251:00
―  HO2S: P0137:00, P0138:00, P013A:00, P0140:00
―  A/F sensor heater: P0031:00, P0032:00
―  HO2S heater: P0037:00, P0038:00
*1: Value can be verified by displaying the PIDs using the M-MDS.
Drive cycle
•  2
Self test type
•  CMDTC self test
Sensor used
•  HO2S
FAIL-SAFE FUNCTION
•  Not applicable.
VEHICLE STATUS WHEN DTCs ARE OUTPUT
•  Illuminates the check engine light
POSSIBLE CAUSE
•  HO2S malfunction
―  HO2S loose
•  A/F sensor malfunction
―  A/F sensor loose
―  Exhaust system leakage
―  A/F sensor deterioration
•  WU-TWC deterioration or malfunction
•  PCM malfunction


System Wiring Diagram

•  Not applicable.

Function Explanation (DTC Detection Outline)

•  The PCM monitors the oxygen storage amount proportional to the catalytic converter purification characteristic.
•  The PCM starts to monitor after recovery (fuel injection starts) from fuel cut control.
•  The PCM temporarily changes the target air/fuel ratio to rich at fuel cut recovery, and detects the response time until the rear HO2S output signal outputs the voltage on the rich side.
•  If the catalytic converter purification characteristic deteriorates, the amount of the time until the rear HO2S detects the voltage on the rich side is shorter compared to the normal purification characteristic. (refer to the following figure)
The PCM detects a catalytic converter malfunction using this characteristic.
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Repeatability Verification Procedure

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*1  :MTX: accelerate in 5th. (accelerate to 89 km/h {55 mph} within 20 s.)/ATX: accelerate in D position. (accelerate to 89 km/h {55 mph} within 20 s.)
*2  :MTX: accelerate in 5th. (accelerate to 45 km/h {28 mph} within 15 s.)/ATX: accelerate in D position. (accelerate to 45 km/h {28 mph} within 15 s.)

PID Item/Simulation Item Used In Diagnosis

PID/DATA monitor item table

Item

Definition

Unit

Condition/Specification
O2S11
A/F sensor input signal
µA
•  Idle (after warm up): Approx. -39 µA
•  Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 3.84 mA
O2S12
HO2S input signal
V
•  Idle (after warm up): 0—1.0 V
•  Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 0 V
RPM
Engine speed
RPM
•  Displays the engine speed
VSS
Vehicle speed
KPH
•  Displays the vehicle speed


Function Inspection Using M-MDS

STEP

INSPECTION

RESULTS

ACTION
1
PURPOSE: VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service Information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
2
PURPOSE: IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA (MODE 2)
•  Is the DTC P0421:00 on FREEZE FRAME DATA (Mode 2)?
Yes
Go to the next step.
No
Go to the troubleshooting procedure for DTC on FREEZE FRAME DATA (Mode 2).
(See DTC TABLE [SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
3
PURPOSE: RECORD VEHICLE STATUS AT TIME OF DTC DETECTION TO UTILIZE WITH REPEATABILITY VERIFICATION
•  Has the FREEZE FRAME DATA (Mode 2)/snapshot data been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA (Mode 2)/snapshot data on the repair order, then go to the next step.
Note
•  Recording can be facilitated using the screen capture function of the PC.
4
PURPOSE: VERIFY A/F SENSOR AND HO2S INPUT SIGNAL
•  Start the engine and warm it up completely.
•  Drive the vehicle under the following conditions.
Warning
•  When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.
•  While performing this step, always operate the vehicle in a safe and lawful manner.
―  After increasing the engine speed to 3,000 rpm, decelerate using engine braking.
•  Access the following PIDs using the M-MDS:
―  O2S11
―  O2S12
•  Is the displayed PID value as follows?
―  O2S11: 0.25 mA or more
―  O2S12: 0.3 V or less
Yes
Go to the troubleshooting procedure to perform the procedure from Step 3.
No
Go to the next step.
5
INSPECT RELATED SENSOR WIRING HARNESS AND CONNECTOR
•  Access the following PIDs using the M-MDS:
―  O2S11
―  O2S12
•  When the PCM, A/F sensor and HO2S are shaken, does the PID value include a PID item which has changed?
Yes
Inspect the related wiring harness and connector.
•  Repair or replace the malfunctioning part.
Go to the troubleshooting procedure to perform the procedure from Step 6.
No
Go to the troubleshooting procedure to perform the procedure from Step 1.


Troubleshooting Diagnostic Procedure

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 7—9
―  Verify that primary malfunction is resolved and there are no other malfunctions.

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
•  Reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Implement the repeatability verification procedure.
•  Perform the Pending Trouble Code Access Procedure.
•  Are any other PENDING CODEs and/or DTCs present?
Yes
Go to the applicable PENDING CODE or DTC inspection.
(See DTC TABLE [SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
Go to the next step.
No
Go to the next step.
7
PURPOSE: VERIFY CATALYTIC CONVERTER MALFUNCTION
•  Clear the DTC from the PCM memory using the M-MDS.
•  Implement the repeatability verification procedure.
•  Perform the Pending Trouble Code Access Procedure.
•  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 2.0, SKYACTIV-G 2.5].)
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.
•  Implement the repeatability verification procedure.
•  Perform the Pending Trouble Code Access Procedure.
•  Is the PENDING CODE for this DTC present?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the PCM.
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 [SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
No
DTC troubleshooting completed.