Dtc P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Engine. Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35
3Zr-Fae Engine Control System. Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35

DESCRIPTION

CATALYST LOCATION

CONFIRMATION DRIVING PATTERN

CONDITIONING FOR SENSOR TESTING

INSPECTION PROCEDURE

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420)

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (INJECTION VOLUME CONTROL)

INSPECT FOR EXHAUST GAS LEAK

REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST)

INSPECT FOR EXHAUST GAS LEAK

DTC P0420 Catalyst System Efficiency Below Threshold (Bank 1)


DESCRIPTION

The ECM uses sensors mounted in front of and behind the Three Way Catalytic Converter (TWC) to monitor its efficiency.
The first sensor, the Air Fuel Ratio (A/F) sensor, sends pre-catalyst information to the ECM. The second sensor, the Heated Oxygen (HO2) sensor, sends post-catalyst information to the ECM.
In order to detect any deterioration in the TWC, the ECM calculates the Oxygen Storage Capacity (OSC) of the TWC. This calculation is based on the voltage output of the HO2 sensor while performing active air fuel ratio control.
The OSC value is an indication of the oxygen storage capacity of the TWC. When the vehicle is being driven with a warm engine, active air fuel ratio control is performed for approximately 15 to 20 seconds. When it is performed, the ECM deliberately sets the air fuel ratio to lean or rich levels. If the rich-lean cycle of the HO2 sensor is long, the OSC becomes greater. There is a direct correlation between the OSCs of the HO2 sensor and the TWC.
The ECM uses the OSC value to determine the state of the TWC. If any deterioration has occurred, it illuminates the MIL and stores the DTC.

DTC No.
DTC Detection Condition
Trouble Area
P0420
The Oxygen Storage Capacity (OSC) value is less than the standard value under active air fuel ratio control (2 trip detection logic).
  1. Front exhaust pipe assembly (TWC: front catalyst)
  2. Center exhaust pipe assembly (TWC: rear catalyst)
  3. Gas leak from exhaust system
  4. Air fuel ratio sensor (sensor 1)
  5. Heated oxygen sensor (sensor 2)

CATALYST LOCATION


Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35.3Zr-Fae Engine Control System.Sfi System. Dtc P0420 Catalyst System Efficiency Below Threshold (Bank 1)


Text in Illustration
*1
Exhaust Manifold
*2
Front Exhaust Pipe Assembly (TWC: Front Catalyst)
*3
Center Exhaust Pipe Assembly (TWC: Rear Catalyst)
*4
Tail Exhaust Pipe

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. Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35.3Zr-Fae Engine Control System.Sfi System. Dtc P0420 Catalyst System Efficiency Below Threshold (Bank 1)

  2. (a) Connect the intelligent tester to the DLC3.
  3. (b) Turn the ignition switch to ON and turn the intelligent tester on.
  4. (c) Enter the following menus: Powertrain / Engine and ECT / DTC / Clear.
  5. (d) Clear the DTCs (if output).
  6. (e) Enter the following menus: Powertrain / Engine and ECT / Data List / Catalyst Monitor.
  7. (f) Check that Catalyst Monitor is Incmpl (incomplete).
  8. (g) Start the engine and warm it up.
  9. (h) Drive the vehicle at between 64 km/h and 113 km/h (40 mph and 70 mph) for at least 10 minutes.
  10. (i) The monitor items will change to Compl (Complete) as Catalyst Monitor operates.
  11. (j) Enter the following menus: Powertrain / Engine and ECT / DTC / Pending; and then check if any DTCs (any pending DTCs) are output.
HINT:
If Catalyst Monitor does not change to Compl (Complete), and no pending DTCs are output, 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 (A/F) and Heated Oxygen (HO2) sensors. This is in order to activate the sensors sufficiently to obtain the appropriate inspection results.

Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35.3Zr-Fae Engine Control System.Sfi System. Dtc P0420 Catalyst System Efficiency Below Threshold (Bank 1)

  1. (a) Connect the intelligent tester 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 and 2000 rpm alternating at 2 second intervals, check the waveforms of the A/F and HO2 sensors using the tester.
HINT:
  1. If either voltage output of the A/F or HO2 sensor does not fluctuate, or there is noise in the waveform of either sensor, the sensor may be malfunctioning.
  2. If the voltage outputs of both 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 HO2 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).

Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35.3Zr-Fae Engine Control System.Sfi System. Dtc P0420 Catalyst System Efficiency Below Threshold (Bank 1)


INSPECTION PROCEDURE

HINT:
Read freeze frame data using the intelligent tester. 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.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON and turn the tester on.

  1. Enter the following menus: Powertrain / Engine and ECT / DTC.

  1. Read the DTCs.

    Result
    Result
    		Proceed to
    DTC P0420 is output
    		A
    P0420 and other DTCs are output
    		B
    HINT:
    If any DTCs other than P0420 are output, troubleshoot those DTCs first.


B
GO TO DTC CHART (RAV4_ACA30 RM000000PDF0CDX.html)
A


2.PERFORM ACTIVE TEST USING INTELLIGENT TESTER (INJECTION VOLUME CONTROL)

  1. Connect the intelligent tester to the DLC3.

  1. Start the engine and turn the tester on.

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

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

  1. Perform the Control the Injection Volume for A/F sensor operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).

  1. Monitor the voltage outputs of the A/F and HO2 sensors (AFS Voltage B1 S1 and O2S B1 S2) displayed on the tester.

    HINT:
    1. The Control the Injection Volume for A/F sensor operation decreases the fuel injection volume by 12.5% or increases the injection volume by 25%.
    2. Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

    Standard:

    Tester Display
    (Sensor)
    		Injection Volume
    		Status
    		Voltage
    AFS Voltage B1 S1
    (A/F)
    		+25%
    		Rich
    		Below 3.1 V
    AFS Voltage B1 S1
    (A/F)
    		-12.5%
    		Lean
    		Higher than 3.4 V
    O2S B1 S2
    (HO2)
    		+25%
    		Rich
    		Higher than 0.55 V
    O2S B1 S2
    (HO2)
    		-12.5%
    		Lean
    		Below 0.4 V

    Result
    Status
    AFS Voltage B1 S1
    		Status
    O2S B1 S2
    		A/F Condition and A/F and
    HO2 Sensors Conditions
    		Misfires
    		Main Suspected Trouble Area
    		Proceed to
    Lean/Rich
    		Lean/Rich
    		Normal
    		-
    1. Three Way Catalytic Converter (TWC)
    2. Gas leak from exhaust system
    		A
    Lean
    		Lean/Rich
    		A/F sensor malfunction
    		-
    1. A/F sensor
    		B
    Rich
    		Lean/Rich
    		A/F sensor malfunction
    		-
    1. A/F sensor
    Lean/Rich
    		Lean
    		HO2 sensor malfunction
    		-
    1. HO2 sensor
    2. Gas leak from exhaust system
    		C
    Lean/Rich
    		Rich
    		HO2 sensor malfunction
    		-
    1. HO2 sensor
    2. Gas leak from exhaust system
    Lean
    		Lean
    		Actual air fuel ratio lean
    		May occur
    1. Extremely rich or lean actual air fuel ratio
    2. Gas leak from exhaust system
    		D
    Rich
    		Rich
    		Actual air fuel ratio rich
    		-
    1. Extremely rich or lean actual air fuel ratio
    2. Gas leak from exhaust system
    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 voltage is consistently below 3.1 V, and the O2S voltage 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 air fuel ratio sensor and heated oxygen sensor alternates correctly.


B
REPLACE AIR FUEL RATIO SENSOR (RAV4_ACA30 RM000002WUR027X.html)

C
Go to step 5

D
CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO, REPAIR CAUSE AND GO TO NEXT STEP (RAV4_ACA30 RM000000WC30FTX.html)
A


3.INSPECT FOR EXHAUST GAS LEAK

  1. Inspect for exhaust gas leakage.

    OK:
    No gas leakage.


NG
REPAIR OR REPLACE EXHAUST GAS LEAK POINT
OK


4.REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST)

  1. Replace the front exhaust pipe assembly (RAV4_ACA30 RM000001XBN01BX.html).


NEXT

REPLACE CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) (RAV4_ACA30 RM000001XBN01BX.html)

5.INSPECT FOR EXHAUST GAS LEAK

  1. Inspect for exhaust gas leakage.

    OK:
    No gas leakage.


NG
REPAIR OR REPLACE EXHAUST GAS LEAK POINT
OK

REPLACE HEATED OXYGEN SENSOR (RAV4_ACA30 RM000001ROP00TX.html)