Brand:

Toyota

Model Name:

4Runner GRN210 215 UZN210 215

Manual:

Repair Manual

Section:

1Gr-Fe Engine Control System

Title:

Sfi System

  1. Monitor description

  2. Monitor strategy

  3. Typical enabling conditions

  4. Typical malfunction thresholds

  5. Monitor result

  6. Conditioning for sensor testing

  7. Inspection procedure

  8. Check any other dtcs output (in addition to dtc p0420 and/or p0430)

  9. Perform active test by intelligent tester (a/f control)

  10. Check for exhaust gas leakage

DTC P0420 Catalyst System Efficiency Below Threshold (Bank 1)

DTC P0430 Catalyst System Efficiency Below Threshold (Bank 2)


​

MONITOR 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, rather than the conventional detecting method, which uses the locus ratio.
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 a 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 sets the DTC.

DTC No.
DTC Detection Conditions
Trouble Areas
P0420
OSC value smaller than standard value under active air-fuel ratio control (2 trip detection logic)
  1. Gas leakage from exhaust system
  2. A/F sensor (bank 1 sensor 1)
  3. HO2 sensor (bank 1 sensor 2)
  4. Exhaust manifold (TWC)
P0430
OSC value smaller than standard value under active air-fuel ratio control (2 trip detection logic)
  1. Gas leakage from exhaust system
  2. A/F sensor (bank 2 sensor 1)
  3. HO2 sensor (bank 2 sensor 2)
  4. Exhaust manifold (TWC)
HINT:
  1. Bank 1 refers to the bank that includes cylinder No. 1.
  2. Bank 2 refers to the bank that does not include cylinder No. 1.
  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.

MONITOR STRATEGY


Related DTCs
P0420: Catalyst (Bank 1) Deterioration
P0430: Catalyst (Bank 2) Deterioration
Required Sensors / Components (Main)
Catalyst
Required Sensors / Components (Related)
A/F sensor, Rear HO2S, IAT sensor, MAF meter, Crankshaft position sensor, ECT sensor
Frequency of Operation
Once per driving cycle
Duration
30 seconds
MIL Operation
2 driving cycles
Sequence of Operation
None

TYPICAL ENABLING CONDITIONS


The monitor will run whenever these DTCs are not present
P0011, P0012 (VVT System1-Advance, Retard), P0021, P0022 (VVT System2-Adavance, Retard), P0031, P0032, P0051, P0052 (A/F Sensor Heater Sensor 1), P0037, P0038, P0057, P0058 (O2 Sensor heater Sensor 2), P0100, P0101, P0102, P0103 (MAF Sensor), P0115, P0116, P0117, P0118 (ECT Sensor), P0120, P0121, P0122, P0123, P0220, P0222, P0223 , P2135 (TP Sensor), P0125 (Insufficient ECT for Closed Loop), P0136, P0156 (O2 Sensor 2), P0171,P0172 (Fuel System), P0300, P0301, P0302, P0303, P0304, P0305, P0306 (Misfire), P0335 (CKP Sensor), P0340, P0342, P0343 (CMP Sensor), P0351, P0352, P0353, P0354, P0355, P0356 (Ignitor), P0500 (VSS), P2196, P2198 (A/F Sensor (Rationality)), P2A00, P2A03 (A/F Sensor (Slow Response))
Battery voltage
11 V or more
IAT
-10°C (14°F) or more
ECT
75°C (167°F) or more
Atmospheric pressure coefficient
0.75 or more
Idle
OFF
Engine RPM
Less than 3,200 rpm
A/F sensor
Activated
Fuel system status
Closed loop
Engine load
10 to 70%
All of the following conditions are met
Condition 1, 2 and 3
1. MAF
15 to 70 g/sec.
2. Front catalyst temperature (estimated)
620 to 840°C (1,148 to 1,544°F)
3. Rear catalyst temperature (estimated)
100 to 900°C (212 to 1,652°F)
Rear HO2S
Completed
Shift position
4th or more

TYPICAL MALFUNCTION THRESHOLDS


Oxygen Storage Capacity (OSC) of catalyst
Less than 0.04 g

MONITOR RESULT

Refer to Checking Monitor Status for detailed information (Click here).
The test value and test limit information are described as shown in the following table. Check the monitor result and test values after performing the monitor drive pattern (Click here).
  1. TID (Test Identification Data) is assigned to each emissions-related component.
  2. TLT (Test Limit Type):
    If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
    If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
  3. CID (Component Identification Data) is assigned to each test value.
  4. Unit Conversion is used to calculate the test value indicated on generic OBD ll scan tools.

TID $01: Catalyst (Active A/F control method)
TLT
CID
Unit Conversion
Description of Test Data
Description of Test Limit
1
$01
Multiply by 0.0078
(no dimension)
Oxygen storage capacity (bank 1): Calculated by HO2S sensor 2 output
Malfunction criteria for catalyst deterioration
1
$02
Multiply by 0.0078
(no dimension)
Oxygen storage capacity (bank 2): Calculated by HO2S sensor 2 output
Malfunction criteria for catalyst deterioration

CONDITIONING FOR SENSOR TESTING

HINT:
Perform the operation with the engine speeds and time durations described below prior to check the waveforms of the A/F and HO2 sensors. This is in order to activate the sensors sufficiently to obtain the appropriate inspection results.

Connect the intelligent tester to the DLC3 (Procedure "A"). 4Runner

  1. Connect the intelligent tester to the DLC3 (Procedure "A").
  2. Start the engine and warm it up with all the accessories switched off, until the engine coolant temperature stabilizes (Procedure "B").
  3. Run the engine at an engine speed of between 2,500 rpm and 3,000 rpm for at least 3 minutes (Procedure "C").
  4. While running the engine at 3,000 rpm for 2 seconds and 2,000 rpm for 2 seconds, check the waveforms of the A/F and HO2 sensors using the tester (Procedure "D").
    HINT:
    1. If either of the voltage outputs of the Air-Fuel Ratio (A/F) or Heated Oxygen (HO2) sensor does not fluctuate, or either of the sensors makes a noise, the sensor may be malfunctioning.
    2. If the voltage outputs of both the sensors remain lean or rich, the air-fuel ratio may be extremely lean or rich. In such cases, perform the following A/F CONTROL using the intelligent tester.
    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).

Connect the intelligent tester to the DLC3. 4Runner


A/F CONTROL
The following instructions describe how to conduct the A/F CONTROL operation using an intelligent tester.
HINT:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.

  1. Connect the intelligent tester to the DLC3.

  2. Start the engine and turn the tester on.

  3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.

  4. On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.

  5. Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

  6. Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.

    HINT:
    1. The A/F CONTROL operation lowers 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 voltage:

    Tester Display (Sensor)
    		Injection Volumes
    		Status
    		Voltages
    AFS B1S1 or AFS B2S1 (A/F)
    		+25%
    		Rich
    		Less than 3.0
    AFS B1S1 or AFS B2S1 (A/F)
    		-12.5%
    		Lean
    		More than 3.35
    O2S B1S2 or O2S B2S2 (HO2)
    		+25%
    		Rich
    		More than 0.55
    O2S B1S2 or O2S B2S2 (HO2)
    		-12.5%
    		Lean
    		Less than 0.4
    NOTICE:
    The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.

    Case
    		A/F Sensor (Sensor 1)
    Output Voltage
    		HO2 Sensor (Sensor 2)
    Output Voltage
    		Main Suspected Trouble Area
    1
    		Injection Volume
    +25%
    -12.5%
    		A/F sensor 4Runner
    		Injection Volume
    +25%
    -12.5%
    		A/F sensor 4Runner
    		-
    Output Voltage
    More than 3.35 V
    Less than 3.0 V
    		A/F sensor 4Runner
    		Output Voltage
    More than 0.55 V
    Less than 0.4 V
    		A/F sensor 4Runner
    2
    		Injection Volume
    +25%
    -12.5%
    		A/F sensor 4Runner
    		Injection Volume
    +25%
    -12.5%
    		A/F sensor 4Runner
    1. A/F sensor
    2. A/F sensor heater
    3. A/F sensor circuit
    Output Voltage
    Almost
    no reaction
    		HO2 sensor 4Runner
    		Output Voltage
    More than 0.55 V
    Less than 0.4 V
    		HO2 sensor 4Runner
    3
    		Injection Volume
    +25%
    -12.5%
    		HO2 sensor 4Runner
    		Injection Volume
    +25%
    -12.5%
    		HO2 sensor 4Runner
    1. HO2 sensor
    2. HO2 sensor heater
    3. HO2 sensor circuit
    Output Voltage
    More than 3.35 V
    Less than 3.0 V
    		Injector 4Runner
    		Output Voltage
    Almost
    no reaction
    		Injector 4Runner
    4
    		Injection volume
    +25%
    -12.5%
    		Injector 4Runner
    		Injection Volume
    +25%
    -12.5%
    		Injector 4Runner
    1. Injector
    2. Fuel pressure
    3. Gas leakage from exhaust system
      (Air-fuel ratio extremely lean or rich)
    Output Voltage
    Almost
    no reaction
    		Following the A/F CONTROL procedure enables technicians to check the graph the voltage outputs of both the A/F and HO2 sensors. 4Runner
    		Output Voltage
    Almost
    no reaction
    		Following the A/F CONTROL procedure enables technicians to check the graph the voltage outputs of both the A/F and HO2 sensors. 4Runner
    1. Following the A/F CONTROL procedure enables technicians to check the graph the voltage outputs of both the A/F and HO2 sensors.
    2. To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2, press the YES button and then the ENTER button followed by the F4 button.

INSPECTION PROCEDURE

HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430)

  1. Connect the intelligent tester to the DLC3.

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

  1. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

  1. Read DTCs.

    Result:

    Display (DTC Output)
    		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.


Bnext
GO TO DTC CHART
A
next down

2.PERFORM ACTIVE TEST BY INTELLIGENT TESTER (A/F 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 2,500 rpm for approximately 90 seconds.

  1. Select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.

  1. Perform the A/F CONTROL operation with the engine in an idling condition (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 B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.

    HINT:
    1. The A/F CONTROL operation lowers 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 voltage:

    Tester Display (Sensor)
    		Injection Volumes
    		Status
    		Voltages
    AFS B1S1 or AFS B2S1 (A/F)
    		+25%
    		Rich
    		Less than 3.0
    AFS B1S1 or AFS B2S1 (A/F)
    		-12.5%
    		Lean
    		More than 3.35
    O2S B1S2 or O2S B2S2 (HO2)
    		+25%
    		Rich
    		More than 0.55
    O2S B1S2 or O2S B2S2 (HO2)
    		-12.5%
    		Lean
    		Less than 0.4

    Result:

    Status AFS B1S1 or AFS B2S1
    		Status O2S B1S2 or O2S B2S2
    		A/F Condition and A/F and HO2 Sensor Conditions
    		Misfires
    		Suspected Trouble Areas
    		Proceed to
    Lean/Rich
    		Lean/Rich
    		Normal
    		-
    1. Three-Way Catalytic Converter (TWC)
    2. Gas leakage from exhaust system
    		A
    Lean
    		Lean/Rich
    		A/F sensor malfunction
    		-
    		A/F sensor
    		B
    Rich
    		Lean/Rich
    		A/F sensor malfunction
    		-
    		A/F sensor
    		B
    Lean/Rich
    		Lean
    		HO2 sensor malfunction
    		-
    1. HO2 sensor
    2. Gas leakage from exhaust system
    		C
    Lean/Rich
    		Rich
    		HO2 sensor malfunction
    		-
    1. HO2 sensor
    2. Gas leakage from exhaust system
    		C
    Lean
    		Lean
    		Actual air-fuel ratio lean
    		May occur
    1. Extremely rich or lean actual air-fuel ratio
    2. Gas leakage from exhaust system
    		A
    Rich
    		Rich
    		Actual air-fuel ratio rich
    		-
    1. Extremely rich or lean actual air-fuel ratio
    2. Gas leakage from exhaust system
    		A
    Lean: During A/F CONTROL, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V.
    Rich: During A/F CONTROL, the AFS is consistently less than 3.0 V, and the O2S is consistently more than 0.55 V.
    Lean/Rich: During A/F CONTROL of the ACTIVE TEST, the output voltage of the HO2 sensor alternates correctly.


Bnext
CHECK AND REPLACE AIR FUEL RATIO SENSOR

Cnext
CHECK AND REPLACE HEATED OXYGEN SENSOR, AND CHECK AND REPAIR EXHAUST GAS LEAKAGE
A
next down

3.CHECK FOR EXHAUST GAS LEAKAGE
OK:
No gas leakage.


NGnext
REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK
next down
REPLACE THREE-WAY CATALYTIC CONVERTER (FRONT EXHAUST PIPE)