Toyota Venza: Catalyst System Efficiency Below Threshold (Bank 1) (P0420)

Toyota Venza Service Manual / 1ar-fe Engine Control / Sfi System / Catalyst System Efficiency Below Threshold (Bank 1) (P0420)

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 sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to the ECM.

In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic converter. This calculation is based on the voltage output of the heated oxygen sensor while performing active air fuel ratio control.

The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. 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 cycle of the waveform for the heated oxygen sensor is long, the oxygen storage capacity is great. There is a direct correlation between the heated oxygen sensor and the oxygen storage capacity of the three-way catalytic converter.

The ECM uses the oxygen storage capacity value to determine the state of the three-way catalytic converter. If any deterioration has occurred, the ECM illuminates the MIL and sets the DTC.

DTC No.	DTC Detection Condition	Trouble Area
P0420	The oxygen storage capacity value is less than the standard value under active air fuel ratio control (1 trip detection logic).	Gas leak from exhaust system Air fuel ratio sensor (bank 1 sensor 1) Heated oxygen sensor (bank 1 sensor 2) Exhaust manifold converter sub-assembly (TWC: Front catalyst) and center exhaust pipe assembly (TWC: Rear catalyst)

CATALYST LOCATION

Text in Illustration

*1	Exhaust Manifold Converter Sub-assembly (TWC: Front Catalyst)	*2	Air Fuel Ratio Sensor (Sensor 1)
*3	Heated Oxygen Sensor (Sensor 2)	*4	Front Exhaust Pipe Assembly
*5	Canter Exhaust Pipe Assembly (TWC: Rear Catalyst)	*6	Tail Exhaust Pipe Assembly

NOTICE:

Replace the exhaust manifold converter sub-assembly (*1) and the center exhaust pipe assembly (*5) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor *2 and heated oxygen sensor *3)

MONITOR STRATEGY

Related DTCs	P0420: Catalyst Deterioration
Required Sensors/Components (Main)	Air fuel ratio sensor Heated oxygen sensor
Required Sensors/Components (Related)	Intake air temperature sensor Mass air flow meter Crankshaft position sensor Engine coolant temperature sensor
Frequency of Operation	Once per driving cycle
Duration	Approximately 30 seconds
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not stored	P0010 (Camshaft Timing Oil Control Valve) P0011 (VVT System - Advance) P0012 (VVT System - Retard) P0016 (VVT System - Misalignment) P0013 (Exhaust Camshaft Timing Oil Control Valve) P0014 (Exhaust VVT System - Advance) P0015 (Exhaust VVT System - Retard) P0017 (Exhaust VVT System - Misalignment) P0031, P0032, P101D (Air Fuel Ratio Sensor Heater) P0037, P0038, P102D (Heated Oxygen Sensor Heater) P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air Fuel Ratio Sensor) P0136, P0137, P0138, P0139, P013A, P0607 (Rear Oxygen Sensor) P0102, P0103 (Mass Air Flow Meter) P0115, P0117, P0118 (Engine Coolant Temperature Sensor) P0125 (Insufficient Coolant Temperature for Closed Loop Fuel Control) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle Position Sensor) P0171, P0172 (Fuel System) P0300 - P0304 (Misfire) P0335 (Crankshaft Position Sensor) P0340, P0342, P0343 (Camshaft Position Sensor) P0365, P0367, P0368 (Exhaust Camshaft Position Sensor) P0351 - P0354 (Igniter) P0500 (Vehicle Speed Sensor) P219A, P219C, P219D, P219E, P219F (Air Fuel Ratio Imbalance)
Response rate during fuel cut from rich condition	Completed
Battery voltage	11 V or higher
Intake air temperature	-10°C (14°F) or higher
Engine coolant temperature	75°C (167°F) or higher
Atmospheric pressure	76 kPa(abs) [(570 mmHg(abs)] or higher
Idling	OFF
Engine speed	Less than 3000 rpm
Air fuel ratio sensor status	Activated
Fuel system status	Closed loop
Engine load	10% or more, and less than 90%
All of the following conditions are met	Condition 1, 2 and 3
1. Mass air flow rate	2.5 gm/sec or more, and less than 70 gm/sec
2. Front catalyst temperature (estimated)	615°C (1139°F) or more, and less than 840°C (1544°F)
3. Rear catalyst temperature (estimated)	430°C (806°F) or more, and less than 770°C (1418°F)
Shift position	3rd or higher

TYPICAL MALFUNCTION THRESHOLDS

Oxygen Storage Capacity (OSC) of catalyst (Normalized)

Less than 1

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 DTC P0420. 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.

Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the Techstream on.
Enter the following menus: Powertrain / Engine / Monitor / Current Monitor.
Check that Catalyst Efficiency / Current is Incomplete.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with the shift lever in P [A].
HINT:

In order to keep the idling stable, turn off the A/C and all other electric loads and do not perform any shift operations.
Drive the vehicle at approximately 75 km/h (47 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.
With the shift lever in S, drive the vehicle at 75 km/h (47 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.
Enter the following menus: Powertrain / Engine / Monitor / Current Monitor / O2 Sensor / RL F/C B1S2 [D].
Check the Test Value for RL F/C B1S2.
HINT:
- 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.
Turn the ignition switch off and wait for at least 30 seconds [F].
Turn the ignition switch to ON and turn the Techstream on.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [G].
Drive the vehicle at approximately 75 km/h (47 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.
Enter the following menus: Powertrain / Engine / Trouble Codes [I].
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.
Drive the vehicle at approximately 100 km/h (62 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.
Enter the following menus: Powertrain / Engine / Trouble Codes [K].
Check if any DTCs are stored.
HINT:

If the monitor item does not change to Complete, and no DTCs are stored, extend the driving time.
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 air fuel ratio sensor and heated oxygen sensor. 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 for 2 seconds and 2000 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the Techstream.

HINT:

If either voltage output of the air fuel ratio or heated oxygen sensor does not fluctuate, or there is 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, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume.
If the three-way catalytic converter has deteriorated, the heated oxygen sensor (located behind the three-way catalytic converter) voltage output fluctuates up and down frequently, even under normal driving conditions (active air fuel ratio control is not performed).

CAUTION / NOTICE / HINT

HINT:

Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.
If a malfunction cannot be found when troubleshooting DTC P0420, a lean or rich abnormality may be the cause. Perform troubleshooting by following the inspection procedure for P0171 (System Too Lean) and P0172 (System Too Rich).
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.

PROCEDURE

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

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

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

(e) Read the DTCs.

Result	Proceed to
DTC P0420 is output	A
DTC P0420 and other DTCs are output	B

HINT:

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

GO TO DTC CHART

2.	PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)

(a) Connect the Techstream to the DLC3.

(b) Start the engine and warm it up.

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

(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume.

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

(g) Monitor the voltage outputs of the air fuel ratio sensor and heated oxygen sensor (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.

HINT:

Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations.
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:

Techstream Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 (Air fuel ratio)	+12%	Rich	Below 3.1 V
AFS Voltage B1S1 (Air fuel ratio)	-12%	Lean	Higher than 3.4 V
O2S B1S2 (Heated oxygen)	+12%	Rich	Higher than 0.55 V
O2S B1S2 (Heated oxygen)	-12%	Lean	Below 0.4 V

Status AFS Voltage B1S1	Status O2S B1S2	Air Fuel Ratio Condition and Air Fuel Ratio and Heated Oxygen Sensors Condition	Misfire	Main Suspected Trouble Area	Proceed to
Lean/Rich	Lean/Rich	Normal	-	Three-way catalytic converter Gas leak 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 leak from exhaust system	C
Lean/Rich	Rich	Heated oxygen sensor malfunction	-	Heated oxygen sensor Gas leak from exhaust system	C
Lean	Lean	Actual air fuel ratio lean	May occur	Extremely lean actual air fuel ratio Gas leak from exhaust system	D
Rich	Rich	Actual air fuel ratio rich	-	Extremely rich actual air fuel ratio Gas leak from exhaust system	D

Lean: During Control the Injection Volume, the air fuel ratio sensor output voltage (AFS Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2) is consistently below 0.4 V.

Rich: During Control the Injection Volume, the AFS Voltage B1S1 is consistently below 3.1 V, and the O2S B1S2 is consistently higher than 0.55 V.

Lean/Rich: During Control the Injection Volume of the Active Test, the output voltage of the heated oxygen sensor alternates correctly.

GO TO STEP 5

GO TO STEP 6

GO TO STEP 8

3.	CHECK FOR EXHAUST GAS LEAK

(a) Check for exhaust gas leaks.

OK:

No gas leaks.

GO TO STEP 10

4.	REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST))

NOTICE:

Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

HINT:

Confirm the replacement parts, referring to the illustration in the Catalyst Location.

(a) Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) (See page ).

(b) Replace the center exhaust pipe assembly (TWC: Rear catalyst) (See page ).

END

5.	REPLACE AIR FUEL RATIO SENSOR

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

HINT:

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

GO TO STEP 11

6.	CHECK FOR EXHAUST GAS LEAK

(a) Check for exhaust gas leaks.

OK:

No gas leaks.

GO TO STEP 10

7.	REPLACE HEATED OXYGEN SENSOR

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

HINT:

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

GO TO STEP 11

8.	CHECK FOR EXHAUST GAS LEAK

(a) Check for exhaust gas leaks.

OK:

No gas leaks.

GO TO STEP 10

9.	CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO

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

GO TO STEP 11

10.	REPAIR OR REPLACE EXHAUST GAS LEAK POINT

(a) Repair or replace exhaust gas leak point.

HINT:

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

11.	CHECK WHETHER DTC OUTPUT RECURS (DTC P0420)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Clear the DTCs (See page ).

(e) Turn the ignition switch off and wait for at least 30 seconds.

(f) Turn the ignition switch to ON.

(g) Turn the Techstream on.

(h) Start the engine.

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

(j) Enter the following menus: Powertrain / Engine / Trouble Codes.

(k) Read the DTCs.

Result

Proceed to

DTC P0420 is output

DTC is not output

(No pending DTCs output)

END

12.	REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND FRONT EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST))

NOTICE:

Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

HINT:

Confirm the replacement parts, referring to the illustration in the Catalyst Location.

(a) Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) (See page ).

(b) Replace the center exhaust pipe assembly (TWC: Rear catalyst) (See page ).

END

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