Toyota Tundra. Manual — part 1569

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.

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 sets the DTC.

DTC DETECTION CONDITION AND TROUBLE AREA REFERENCE CHART

DTC

DTC Detection Condition

Trouble Area

P0420

OSC value smaller than standard
value under active air-fuel ratio
control (2 trip detection logic)



Gas leakage from exhaust
system



Air-Fuel Ratio (A/F) sensor
(for Bank 1 Sensor 1)



Heated Oxygen (HO2)
sensor (for Bank 1 Sensor 2)



Front No. 2 exhaust pipe
sub-assembly and front No. 3
exhaust pipe sub-assembly
(for Regular Cab Standard
Deck)



Front No. 2 exhaust pipe
assembly (except Regular
Cab Standard Deck)



Fuel pressure switching
valve



Fuel pressure regulator



Fuel pressure regulator for
high pressure

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

HINT:



Bank 1 refers to the bank that includes No. 1 cylinder.



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



Sensor 1 refers to the sensor closest to the engine assembly.



Sensor 2 refers to the sensor farthest away from the engine assembly.

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL ENABLING CONDITIONS

P0430

OSC value smaller than standard
value under active air-fuel ratio
control (2 trip detection logic)



Gas leakage from exhaust
system



Air-Fuel Ratio (A/F) sensor
(for Bank 2 Sensor 1)



Heated Oxygen (HO2)
sensor (for Bank 2 Sensor 2)



Front exhaust pipe assembly



Fuel pressure switching
valve



Fuel pressure regulator



Fuel pressure regulator for
high pressure

Related DTCs

P0420: Catalyst Deterioration (for Bank 1)
P0430: Catalyst Deterioration (for Bank 2)

Required Sensors/Components
(Main)

A/F sensor and HO2 sensor

Required Sensors/Components
(Related)

Intake air temperature sensor, mass air flow meter, crankshaft position
sensor and engine coolant temperature sensor

Frequency of Operation

Once per driving cycle

Duration

About 30 seconds

MIL Operation

2 driving cycles

Sequence of Operation

None

P0010, P0020 (VVT Oil Control Valve)
P0011, P0021 (VVT System - Advance)
P0012, P0022 (VVT System - Retard)
P0016, P0018 (VVT System - Misalignment)
P0013, P0023 (Exhaust VVT Oil Control Valve)
P0014, P0024 (Exhaust VVT System - Advance)

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

Monitor runs whenever
following DTCs not present

P0015, P0025 (Exhaust VVT System - Retard)
P0017, P0019 (Exhaust VVT System - Misalignment)
P0031, P0032, P0051, P0052 (Air Fuel Ratio Sensor Heater)
P0037, P0038, P0057, P0058 (Rear Oxygen Sensor Heater)
P2195, P2196, P2197, P2198, P2237, P2238, P2239, P2240, P2241,
P2242, P2252, P2253, P2255, P2256, P2A00, P2A03 (Air Fuel Ratio
Sensor)
P0136, P0137, P0138, P0139, P0156, P0157, P0158, P0159, P0607 (Rear
Oxygen Sensor)
P0102, P0103 (Mass Air Flow Sensor)
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, P0174, P0175 (Fuel System)
P0301 - P0308 (Misfire)
P0335 (Crankshaft Position Sensor)
P1340 (Camshaft Position Sensor)
P0340, P0342, P0343, P0345, P0347, P0348 (VVT Sensor)
P0365, P0367, P0368, P0390, P0392, P0393 (Exhaust VVT Sensor)
P0351 - P0358 (Igniter)
P0412, P0415, P0418, P0419, P1613, P1614 (Secondary Air Injection
System Control)
P2440, P2441, P2442, P2443, P2444, P2445, P2446, P2447 (Secondary
Air Injection System)
P0500 (Vehicle Speed Sensor)

Battery voltage

11 V or more

Intake air temperature

-10°C (14°F) or more

Engine coolant temperature

75°C (167°F) or more

Atmospheric pressure

76 kPa (570 mmHg) or more

Idling

OFF

Engine speed

Less than 3200 RPM

A/F sensor status

Activated

Fuel system status

Closed loop

Engine load

10 to 75%

All of following conditions
(a), (b) and (c) met

-

(a) Mass air flow rate

7.5 to 75 g/sec.

(b) Estimated front catalyst
temperature

575 to 820°C (1067 to 1508°F)

(c) Estimated rear catalyst
temperature

400 to 700°C (752 to 1292°F)

Rear HO2 sensor heater
monitor

Completed

Shift position

4th or higher

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

TYPICAL MALFUNCTION THRESHOLDS

TYPICAL MALFUNCTION THRESHOLDS

MONITOR RESULT

Refer to CHECKING MONITOR STATUS .

CONFIRMATION DRIVING PATTERN

HINT:

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

Fig. 166: Vehicle Speed Driving Pattern
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

1. Connect the Techstream to the DLC3.

2. Turn the ignition switch to ON.

3. Turn the Techstream on.

Oxygen Storage Capacity (OSC) of Three-Way Catalytic Converter (TWC)

Less than 0.12 g

NOTE:

This test will not be completed if the vehicle is driven at absolutely constant
speed such as with cruise control activated.
(Note: Even if vehicle stops during driving pattern, test can be resumed)

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra