Toyota Tundra Service Manual: Catalyst System Efficiency Below Threshold (Bank 1) (P0420,P0430)

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.

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.

CATALYST LOCATION

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

MONITOR RESULT

Refer to Checking Monitor Status (See page ).

CONFIRMATION DRIVING PATTERN

HINT:

• It is necessary that the response of the heated oxygen sensor is normal in order to confirm DTCs P0420 and P0430. Therefore, perform the driving pattern for the heated oxygen sensor monitor before performing the drive pattern for the catalyst efficiency monitor.
• Performing this confirmation driving pattern will activate the catalyst efficiency monitor. This is very useful for verifying the completion of a repair.

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
5. Turn the ignition switch off and wait for at least 30 seconds.
6. Turn the ignition switch to ON and turn the Techstream on.
7. Enter the following menus: Powertrain / Engine and ECT / Monitor / Current Monitor.
8. Check that Catalyst Efficiency / Current 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 at approximately 60 km/h (37 mph) for 10 minutes or more [B].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    HINT:

    Drive the vehicle while keeping the engine load as constant as possible.

11. With the shift lever in S, drive the vehicle at 60 km/h (37 mph), and then decelerate the vehicle by releasing the accelerator pedal for 5 seconds or more to perform the fuel-cut [C].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

12. Enter the following menus: Powertrain / Engine and ECT / Monitor / Current Monitor / O2 Sensor / RL F/C B1S2, RL F/C B2S2 [D].
13. Check the Test Value for RL F/C B1S2, RL F/C B2S2.
    • If Test Value displays a value larger than 0, perform the following procedure, as the O2 sensor monitor is finished.
    • If Test Value displays 0, perform step [C] until it displays a value larger than 0, as the O2 sensor monitor is not finished.
14. Turn the ignition switch off and wait for at least 30 seconds [F].
15. Turn the ignition switch to ON and turn the Techstream on.
16. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [G].
17. Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [H].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    HINT:

    • Drive the vehicle while keeping the engine load as constant as possible.
    • The monitor item will change to Complete as the Catalyst Efficiency monitor operates [I].
18. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
19. Check if any DTCs are stored.

    HINT:

    If the monitor item does not change to Complete, and no DTCs are stored, perform the following procedure.

20. Drive the vehicle at a speed between 75 and 100 km/h (47 and 63 mph) for 10 minutes or more [J].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    HINT:

    • Drive the vehicle while keeping the engine load as constant as possible.
    • The monitor item will change to Complete as the Catalyst Efficiency monitor operates [K].
21. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
22. Check if any DTCs are stored.

    HINT:

    If the monitor item does not change to Complete, and no DTCs are stored, drive the vehicle again under an increased load.

23. If no DTC is output, perform a universal trip and check for permanent DTCs (See page ).

    HINT:

    • If a permanent DTC is output, the system is malfunctioning.
    • If no permanent DTC is output, the system is normal.

CONDITIONING FOR SENSOR TESTING

HINT:

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

• (a) Connect the Techstream to the DLC3.
• (b) Start the engine and warm it up with all the accessories switched OFF until the engine coolant temperature stabilizes.
• (c) Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes.
• (d) While running the engine at 3000 rpm and 2000 rpm at 2 second intervals, check the waveforms of the A/F and HO2 sensors using the Techstream.

HINT:

• If the voltage output of either the Air-Fuel Ratio (A/F) or Heated Oxygen (HO2) sensor does not fluctuate, or there is a noise in the waveform of either sensor, the sensor may be malfunctioning.
• 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 Active Test Control the Injection Volume for A/F Sensor using the Techstream.
• 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).

CAUTION / NOTICE / HINT

HINT:

• If a malfunction cannot be found when troubleshooting DTC P0420 or 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).
• Read freeze frame data using the Techstream. 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.
• Bank 1 refers to the bank that includes the No. 1 cylinder*.

  *: The No. 1 cylinder is the cylinder which is farthest from the transmission.

• Bank 2 refers to the bank that does not include the No. 1 cylinder.

PROCEDURE

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read DTCs.

HINT:

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

B

GO TO DTC CHART

A

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Turn the Techstream on.

(d) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

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

(f) 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).

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

HINT:

• Change the fuel injection volume within the range of -12.5% to +12.5%.
• Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
• 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.
• If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

Standard:

Lean: During the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor output voltage (AFS Voltage) is consistently more than 3.4 V, and the heated oxygen sensor output voltage (O2S) is consistently less than 0.4 V.

Rich: During the Control the Injection Volume for A/F Sensor Active Test, the AFS Voltage is consistently less than 3.1 V, and the O2S is consistently more than 0.55 V.

Lean/Rich: During the Control the Injection Volume for A/F Sensor Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternate correctly.

B

GO TO STEP 7

C

GO TO STEP 8

D

GO TO STEP 10

A

(a) Check for exhaust gas leaks.

OK:

No gas leaks.

HINT:

Perform "Inspection After Repair" after repairing or replacing the exhaust system (See page ).

NG

REPAIR OR REPLACE EXHAUST GAS LEAK POINT

OK

(a) Connect the Techstream to the DLC3.

(b) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

HINT:

• When performing the Active Test, make sure the shift lever is in P or N.
• The A/C switch and all accessory switches should be off.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

(e) Confirm the Throttle Idle Position is ON and check the engine idling condition and MAP values in the Data List while performing the Active Test.

HINT:

• Do not leave the EGR valve open for 10 seconds or more during the Active Test.
• Be sure to return the EGR valve to step 0 when the Active Test is completed.

OK:

MAP and idling condition change in response to EGR step position as follows.

Standard:

OK

GO TO STEP 6

NG

(a) Remove the EGR valve assembly (See page ).

(b) Check if the EGR valve is stuck open.

OK:

EGR valve is tightly closed.

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly (See page ).

NG

REPLACE EGR VALVE ASSEMBLY

OK

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON and turn the Techstream on.

(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(d) Read the DTCs.

B

REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST)

A

REPLACE FRONT NO. 2 EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST)

(a) Replace the air fuel ratio sensor (See page ).

HINT:

Perform "Inspection After Repair" after replacing the air fuel ratio sensor (See page ).

NEXT

GO TO STEP 14

(a) Check for exhaust gas leaks.

OK:

No gas leaks.

HINT:

Perform "Inspection After Repair" after repairing or replacing the exhaust system (See page ).

NG

REPAIR OR REPLACE EXHAUST GAS LEAK POINT

OK

(a) Replace the heated oxygen sensor (See page ).

HINT:

Perform "Inspection After Repair" after replacing the heated oxygen sensor (See page ).

NEXT

GO TO STEP 14

(a) Check for exhaust gas leaks.

OK:

No gas leaks.

HINT:

Perform "Inspection After Repair" after repairing or replacing the exhaust system (See page ).

NG

REPAIR OR REPLACE EXHAUST GAS LEAK POINT

OK

(a) Connect the Techstream to the DLC3.

(b) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

HINT:

• When performing the Active Test, make sure the shift lever is in P or N.
• The A/C switch and all accessory switches should be off.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

(e) Confirm the Throttle Idle Position is ON and check the engine idling condition and MAP values in the Data List while performing the Active Test.

HINT:

• Do not leave the EGR valve open for 10 seconds or more during the Active Test.
• Be sure to return the EGR valve to step 0 when the Active Test is completed.

OK:

MAP and idling condition change in response to EGR step position as follows.

Standard:

OK

CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO

NG

(a) Remove the EGR valve assembly (See page ).

(b) Check if the EGR valve is stuck open.

OK:

EGR valve is tightly closed.

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly (See page ).

NG

REPLACE EGR VALVE ASSEMBLY

OK

(a) Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P0171 Inspection Procedure (See page ).

NEXT

(a) Connect the Techstream to the DLC3.

(b) Clear the DTCs (See page ).

(c) Turn the ignition switch off.

(d) Turn the ignition switch to ON and turn the Techstream on.

(e) Start the engine and warm it up.

(f) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(g) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(h) Read the DTCs.

B

END

A

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON and turn the Techstream on.

(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(d) Read the DTCs.

B

REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST)

A

REPLACE FRONT NO. 2 EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST)