Dtc P0420 Catalyst System Efficiency Below Threshold (Bank 1)

DESCRIPTION

CATALYST LOCATION

CONFIRMATION DRIVING PATTERN

CONDITIONING FOR SENSOR TESTING

INSPECTION PROCEDURE

CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430)

PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)

INSPECT FOR EXHAUST GAS LEAK

INSPECT EXHAUST FOR GAS LEAK

CHECK DTC OUTPUT (DTC P0420 AND/OR P0430)

REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH (TWC: FRONT CATALYST)

REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH (TWC: FRONT CATALYST)

DESCRIPTION

HINT:

1. Bank 1 refers to the bank that includes the No. 1 cylinder.
   
2. Bank 2 refers to the bank that does not include the No. 1 cylinder.
   
3. Sensor 1 refers to the sensor closest to the engine assembly.
   
4. Sensor 2 refers to the sensor farthest away from the engine assembly.
   

CATALYST LOCATION

CONFIRMATION DRIVING PATTERN

HINT:

Performing this confirmation driving pattern will activate the catalyst monitor. This is very useful for verifying the completion of a repair.

1. Connect the GTS to the DLC3.
   
2. Turn the engine switch on (IG).
   
3. Turn the GTS on.
   
4. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
   
5. Turn the engine switch off and wait for at least 30 seconds.
   
6. Turn the engine switch on (IG) and turn the GTS on.
   
7. Enter the following menus: Powertrain / Engine and ECT / Monitor.
   
8. Check that Catalyst / Status2 is Incomplete.
   
9. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].
   
10. Drive the vehicle between 40 and 70 mph (64 and 113 km/h) for 10 minutes or more [B].
    
11. The monitor items will change to Complete as the catalyst monitor operates.
    
12. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
    
13. Check if any DTCs (pending DTCs) are stored.
    

HINT:

If Catalyst does not change to Complete, and no pending DTCs are stored, extend the driving time.

CONDITIONING FOR SENSOR TESTING

HINT:

Perform the operation with the engine speeds and time durations described below prior to checking the waveforms of the air fuel ratio and heated oxygen sensors. This is in order to activate the sensors sufficiently to obtain the appropriate inspection results.

1. (a) Connect the GTS to the DLC3.
   
2. (b) Start the engine and warm it up with all the accessories switched off until the engine coolant temperature stabilizes.
   
3. (c) Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes.
   
4. (d) While running the engine at 3000 rpm for 2 seconds, and then 2000 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the GTS.
   

HINT:

1. If either of the voltage outputs of the air fuel ratio or heated oxygen sensor does not fluctuate, or either of the sensors makes a noise, the sensor may be malfunctioning.
   
2. If the voltage outputs of both of the sensors remain lean or rich, the air-fuel ratio may be extremely lean or rich. In such cases, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
   
3. If the Three-Way Catalytic Converter (TWC) has deteriorated, the heated oxygen sensor (located behind the TWC) voltage output fluctuates up and down frequently, even under normal driving conditions (active air-fuel ratio control is not performed).
   

INSPECTION PROCEDURE

HINT:

Malfunctioning areas can be identified by performing the Control the Injection Volume for air fuel ratio sensor function provided in the Active Test. The Control the Injection Volume for air fuel ratio sensor function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for air fuel ratio sensor operation using the GTS.

1. Connect the GTS to the DLC3.
   
2. Start the engine and turn the GTS on.
   
3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
   
4. On the GTS, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
   
5. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
   
6. Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the GTS.
   

HINT:

1. The Control the Injection Volume for air fuel ratio sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
   
2. Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
   

NOTICE:

The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

Case	Air Fuel Ratio Sensor (Sensor 1) Output Voltage	Heated Oxygen Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
1			-
2			Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3			Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4			Fuel injector assembly Fuel pressure Gas leakage from exhaust system (air fuel ratio extremely rich or lean)

1. Following the Control the Injection Volume for air fuel ratio sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
   
2. To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.
   

HINT:

1. If a malfunction cannot be found when troubleshooting DTC P0420, P0430 a lean or rich abnormality may be the cause. Perform troubleshooting by following the inspection procedure for P0171, P0174 (System Too Lean) and P0172, P0175 (System Too Rich).
   
2. Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
   

1. Connect the GTS to the DLC3.
   

2. Turn the engine switch on (IG) and turn the GTS on.
   

3. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
   

4. Read DTCs.
   
   

   Result

   Result	Proceed to
   P0420 and/or P0430	A
   P0420 and/or P0430 and other DTCs	B

   HINT:

   If any DTCs other than P0420 or P0430 are output, troubleshoot those DTCs first.

1. Connect the GTS to the DLC3.
   

2. Start the engine and turn the GTS on.
   

3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
   

4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
   

5. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
   

6. Monitor the voltage outputs of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the GTS.
   

   HINT:

   1. The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
      
   2. Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
      
      

      Standard:

      
      

      GTS Display (Sensor)	Injection Volume	Status	Voltage
      AFS Voltage B1S1 or AFS Voltage B2S1 (Air fuel ratio sensor)	+12.5%	Rich	Below 3.1 V
      AFS Voltage B1S1 or AFS Voltage B2S1 (Air fuel ratio sensor)	-12.5%	Lean	Higher than 3.4 V
      O2S B1S2 or O2S B2S2 (Heated oxygen sensor)	+12.5%	Rich	Higher than 0.55 V
      O2S B1S2 or O2S B2S2 (Heated oxygen sensor)	-12.5%	Lean	Below 0.4 V

      
      

      Result

      Status of AFS Voltage B1S1 or AFS Voltage B2S1	Status of O2S B1S2 or O2S B2S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor and Heated Oxygen Sensor Condition	Misfire	Main Suspected Trouble Area	Proceed to
      Lean/Rich	Lean/Rich	Normal	-	Three-Way Catalytic Converter (TWC) Gas leakage from exhaust system	A
      Lean	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor	B
      Rich	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor	B
      Lean/Rich	Lean	Heated oxygen sensor malfunction	-	Heated oxygen sensor Gas leakage from exhaust system	C
      Lean/Rich	Rich	Heated oxygen sensor malfunction	-	Heated oxygen sensor Gas leakage from exhaust system	C
      Lean	Lean	Actual air-fuel ratio lean	May occur	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	D
      Rich	Rich	Actual air-fuel ratio rich	-	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	D

      Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (AFS) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S) is consistently below 0.4 V.
      Rich: During Control the Injection Volume for A/F Sensor, the AFS is consistently below 3.1 V, and the O2S is consistently higher than 0.55 V.
      Lean/Rich: During Control the Injection Volume for A/F Sensor of the Active Test, the output voltage of the heated oxygen sensor alternates correctly.
      

   HINT:

   for Automatic Transmission

   Perform "Inspection After Repair" after replacing the air fuel ratio sensor (LandCruiser RM000004NJC03SX.html).

OK:

No gas leakage.

HINT:

for Automatic Transmission

Perform "Inspection After Repair" after repairing or replacing the exhaust system (LandCruiser RM000004NJC03SX.html).

OK:

No gas leakage.

HINT:

for Automatic Transmission

Perform "Inspection After Repair" after repairing or replacing the exhaust system (LandCruiser RM000004NJC03SX.html).

1. According to the DTCs output in the Check for Any Other DTCs Output step, proceed to the next step by referring to the table below.
   

   Result

   Result	Proceed to
   P0420	A
   P0430	B
   P0420 and P0430	A and B

1. Replace the exhaust manifold sub-assembly RH (LandCruiser RM00000456G00XX.html).
   

1. Replace the exhaust manifold sub-assembly LH (LandCruiser RM00000456G00XX.html).