2001 TOYOTA SEQUOIA O2 sensor

A21429
ECM
No.1 Ignition Coil with Igniter
No. 2 Ignition
Coil with Igniter Crankshaft
Position
Sensor
Camshaft
Position
Sensor
Other Sensors:
No. 3 Ignition
Coil with Igniter
No. 4 Ignition
Coil with Igniter
No. 5 Ignition
Coil with Igniter
No. 6 Ignition
Coil with Igniter
No. 7 Ignition
Coil with Igniter
No. 8 Ignition
Coil with Igniter
TA C
To TachometerFrom Battery
Igniter
Ignition CoilSpark Plug
No. 1 Cylinder
No. 4 Cylinder
No. 5 Cylinder
No. 6 Cylinder No. 2 Cylinder
No. 3 Cylinder
No. 7 Cylinder
No. 8 Cylinder IGT1
IGF1
IGT2
IGF2
IGT3
IGT4
IGT5
IGT6
IGT7
IGT8 (Engine Coolant Temp.
Sensor, Mass Air Flow
Sensor, Throttle Position
Sensor, etc.)
DI±222
± DIAGNOSTICSENGINE
416 Author: Date:
2005 SEQUOIA (RM1146U)
CIRCUIT DESCRIPTION
These DTCs indicate a malfunction related to primary circuit.
The DIS is a 1±cylinder ignition system which ignites one cylinder with one ignition coil. In the 1±cylinder
ignition system, the one spark plug is connected to the end of the secondary winding. High voltage generated
in the secondary winding is applied directly to the spark plug. The spark of the spark plug passes from the
center electrode to the ground electrode.
The ECM determines the ignition timing and outputs the ignition signals (IGTs) for each cylinder. Using the
IGT, the ECM turns on and off the power transistor inside the igniter and this switches on and off the current
to the primary coil. When the current to the primary coil is cut off, high±voltage is generated in the secondary
coil and this voltage is applied to the spark plugs to create sparks inside the cylinders. As the ECM cuts the
current to the primary coil, the igniter sends back the ignition confirmation signal (IGF) for each cylinder igni-
tion to the ECM.

DI±224
± DIAGNOSTICSENGINE
418 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
P0351No. 1 ignition coil with igniter circuit malfunction
P0352No. 2 ignition coil with igniter circuit malfunction
P0353No. 3 ignition coil with igniter circuit malfunction
RltdDTCP0354No. 4 ignition coil with igniter circuit malfunctionRelated DTCsP0355No. 5 ignition coil with igniter circuit malfunction
P0356No. 6 ignition coil with igniter circuit malfunction
P0357No. 7 ignition coil with igniter circuit malfunction
P0358No. 8 ignition coil with igniter circuit malfunction
Required sensors/componentsIgniter
Frequency of operationContinuous
Duration0.256 sec. + 4 sparks
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
Engine speed±1,500 rpm
Either of the following conditions is met:Condition 1 or 2
1. Following conditions are met:Condition (a) and (b)
(a) Engine speed±500 rpm
(b) Battery voltage6 V±
2. Following conditions are met:Condition (a) and (b)
(a) Engine speed500 rpm±
(b) Battery voltage10 V±
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
ºIgnition signal fail countºMore than 2
ºIgnition signal fail countº is on the right:When IGF does not return despite sending IGT.
COMPONENT OPERATING RANGE
Standard Value
Confirmed signal number = ignition signal number

B17432
Air PumpPressure
Sensor
Air
Air Injection
Driver (AID)
Air Switching Valve
(ASV)(EASV)Air Switching Valve No.2
(ASV No.2)(ASV1)VSV for Air Injection
Control
ECMEngine Coolant
Temp. Sensor
Mass Air Flow
Meter
Intake Air Temp.
Sensor To Bank 2To Bank1
Air Switching Valve No.2
(ASV No.2)(ASV2)
DI±234
± DIAGNOSTICSENGINE
428 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0412 Secondary Air Injection System Air Switch-
ing Valve ºAº Circuit
CIRCUIT DESCRIPTION
The secondary air injection system pumps air to the exhaust port to accelerate the activation of the catalyst.
The secondary air injection system consists of the ECM, air pump, Air Switching Valve (ASV) (EASV), Air
Switching Valve No.2 (ASV No.2) (ASV1, 2), pressure sensor and air injection driver (AID). The Air Switching
Valve (ASV)(EASV) is an electromagnetic type and Air Switching Valve No.2 (ASV No.2)(ASV1,2) is a vacu-
um type.
The secondary air injection system pumps pressurized air to the exhaust port by the air pump through the
ASV and ASV No.2. The ASV assists the ASV No.2. The ASV No.2 also controls air supply.
The ECM sends signals to the AID, and then the AID operates the air pump and ASV. The pressure sensor
detects pressure and exhaust pulsation in the system when the system operates and when it does not oper-
ate, and sends the data to the ECM.
DTC No.DTC Detection ConditionTrouble Area
P0412
All of the following conditions are met when engine is idling just
after cold start
(1 trip detection logic):
(a) Air injection system does not operate (Air pump OFF and all
ASVs OFF)
(b) Air injection driver diagnostic signal duty is 40%.
Open in air switching valve drive circuit

Short between air switching valve circuit and +B circuit

Air injection driver

Air switching valve

ECM
P0412
All of the following conditions are met when engine is idling just
after cold start
(1 trip detection logic):
(a) Air injection system operates (Air pump ON and all ASVs
ON)
(b) Air injection driver diagnostic signal duty is 40%.

Short between air switching valve circuit and body ground

Air injection driver

Air switching valve

ECM
DIDMV±01

± DIAGNOSTICSENGINE
DI±235
429 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR DESCRIPTION
The air injection driver (AID) detects an open or short in the circuit according to the voltage of the air pump
terminal (VP) and electromagnetic air switching valve terminal (VV), and sends a signal as diagnostic in-
formation to the ECM.
The AID outputs the air switching valve terminal malfunction signal to the ECM if: 1) VV terminal voltage is
low despite the AID receiving the command signal from the ECM to drive the air switching valve terminal or
2) VV terminal voltage is high despite the AID not receiving the command signal from the ECM.
The ECM stores the DTC based on the diagnostic signal from the AID and illuminates the MIL.
MONITOR STRATEGY
Related DTCsP0412Air switching valve circuit malfunction (Second-
ary air injection system)
Required sensors/componentsAir injection driver, Air switching valve
Frequency of operationContinuous
Duration3 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Case 1:
Air pumpOperating
Air switching valveOperating
Battery voltage8 V±
Ignition switchON
StarterOFF
Case 2:
Air pumpNot operating
Air switching valveNot operating
Battery voltage8 V±
Ignition switchON
StarterOFF
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Case 1, 2:
Diagnostic signal duty ratio from air injection driver31 to 48 %
COMPONENT OPERATING RANGE
ParameterStandard Value
Diagnostic signal duty ratio from air injection driver
70 to 90% when secondary air injection system operating
and
0% when secondary air injection system not operating

DI±242
± DIAGNOSTICSENGINE
436 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0418 Air Injection System Air Pump Malfunction
CIRCUIT DESCRIPTION
Refer to DTC P0412 on page DI±234.
DTC No.DTC Detection ConditionTrouble Area
P0418
All of the following conditions are met, when idling just after
cold start. (1 trip detection logic):
(a) Air injection system not operate
(b) Air injection driver outputs air pump malfunction signal (20%
duty signal)
Open in air pump drive circuit

Short between air pump circuit and +B circuit

Air injection driver

ECM
P0418
All of the following conditions are met, when idling just after
cold start.
(1 trip detection logic):
(a) Air injection system operates
(b) Air injection driver outputs air pump malfunction signal (20%
duty signal)

Short between air pump circuit and body ground

Air injection driver

ECM
MONITOR DESCRIPTION
Air Injection Driver (AID) detects an open or short in the air pump and Air Switching Valve (ASV) circuit ac-
cording to the terminal voltage and sends a signal as diagnostic information to the ECM.
When the air injection system operation is required while the engine is warming up, the ECM transmits com-
mand signals to the AID to drive the air pump and ASV.
The AID inputs the command signal from ECM if: 1) VP terminal voltage is low despite the AID inputting the
command signal from the ECM to drive the ASV or 2) VP terminal voltage is high despite the AID not inputting
the command signal from the ECM.
The ECM sets the DTC based on the diagnostic information from the AID.
MONITOR STRATEGY
Related DTCsP0418Air pump range check
Required sensors/componentsAir injection driver, Air pump
Frequency of operationContinuous
Duration3 sec.
MIL operationImmediate
Sequence of operationNone
DIDMW±01

± DIAGNOSTICSENGINE
DI±249
443 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0420 Catalyst System Efficiency Below Threshold
(Bank 1)
DTC P0430 Catalyst System Efficiency Below Threshold
(Bank 2)
MONITOR DESCRIPTION
The ECM uses the two 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 (sensor 1), sends pre±catalyst information to the ECM. The
second sensor, the Heated Oxygen (HO2) sensor (sensor 2), sends post±catalyst information to the ECM.
The ECM compares the information transmitted by these two sensors to determine the efficiency of the TWC
performance and its ability to store oxygen.
When the TWC is functioning properly, the variation in the oxygen concentration in the exhaust gas, after
it has passed through the TWC, is small. In this condition, the voltage output of sensor 2 slowly alternates
between the rich and lean signal voltages (shown in the illustration below). As the TWC performance efficien-
cy deteriorates, its oxygen storage capacity decreases, and the variation in the oxygen concentration in the
exhaust gas increases. As a result, the sensor voltage output fluctuates frequently.
While the catalyst monitor is running, the ECM measures the signal lengths of both sensors 1 and 2, and
calculates the ratio of the signal lengths to determine the extent of the TWC deterioration. If the deterioration
level exceeds the preset threshold, the ECM interprets this as the TWC malfunction. The ECM then illumi-
nates the MIL and sets the DTC.
DTC No.DTC Detecting ConditionTrouble Area
P0420
P0430OSC value smaller than standard value under active air±fuel
ratio control (2 trip detection logic)
Gas leakage on exhaust system
A/F sensor (Bank 1, 2 sensor 1)
Heated oxygen sensor (bank 1, 2 sensor 2)
Three±way catalytic converter
HINT:
Bank 1 refers to the bank that includes cylinder No.1.
Bank 2 refers to the bank that does not include cylinder No.1.
Sensor 1 refers to the sensor mounted in front of the Three±Way Catalytic Converter (TWC) and lo-
cated near the engine assembly.
Sensor 2 refers to the sensor mounted behind the TWC and located far from the engine assembly.
DID87±01

DI±250
± DIAGNOSTICSENGINE
444 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
RltdDTCP0420Bank 1 catalyst is deterioratedRelated DTCsP0430Bank 2 catalyst is deteriorated
Main sensors/componentsFront and rear heated oxygen sensor
Required sensors/componentsRelated sensors/components
Mass air flow meter, Engine coolant temperature
sensor, Engine speed sensor, Intake air tempera-
ture sensor
Frequency of operationOnce per driving cycle
Duration20 sec.
MIL operation2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
Battery voltage11 V±
Intake air temperature±10C (14F)±
Engine coolant temperature75°C (167°F)±
Atmospheric pressure coefficient0.75±
IdleOFF
Engine RPM±3,200 rpm
A/F sensorActivated
Fuel system statusClosed loop
Engine load10 to 70 %
All of the following conditions are metCondition 1, 2 and 3
1. MAF6to 75 g/sec
2. Front catalyst temperature (estimated)620to 830C (1,148 to 1,526F)
3. Rear catalyst temperature (estimated)410 to 830C (770 to 1,526F)
Rear HO2S monitorCompleted
Shift position4th±
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Oxygen storage capacity (OSC) of catalystLess than 0.16

A23541
At least 3 minutes
2 seconds
Check
2 seconds
Engine Speed
3,000 rpm
2,000 rpm
Idling
Ignition Switch OFF(a)(b)(c) (d)
Time
Warming up(d)
± DIAGNOSTICSENGINE
DI±251
445 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR RESULT
Refer to page DI±26 for detailed information.
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 (refer to ºConfirmation Monitorº).
MID (Monitor Identification Data) is assigned to each emissions±related component.
TID (Test Identification Data) is assigned to each test value.
Scaling is used to calculate the test value indicated on generic tools.
Catalyst bank 1 ± Active A/F control method
MIDTIDScalingDescription of Test ValueMinimum Test LimitMaximum Test Limit
$21$A9Multiply by 0.0003
(no dimension)Oxygen storage capacity of catalystMinimum test limit for catalystMaximum test limit for catalyst
Catalyst bank 2 ± Active A/F control method
MIDTIDScalingDescription of Test ValueMinimum Test LimitMaximum Test Limit
$22$A9Multiply by 0.0003
(no dimension)Oxygen storage capacity of catalystMinimum test limit for catalystMaximum test limit for catalyst
WAVEFORMS OF AIR±FUEL RATIO (A/F) AND HEATED OXYGEN (HO2) SEN-
SORS
HINT:
Perform the operation with the engine speeds and time durations described below prior to check the wave-
forms of the A/F and HO2 sensors. This is in order to activate the sensors sufficiently to obtain the appropri-
ate inspection results.
(a) Connect the hand±held tester to the DLC3.
(b) Start the engine and warm it up with all the accessories switched OFF, until the engine coolant temper-
ature stabilizes.
(c) Run the engine at an engine speed of between 2,500 rpm and 3,000 rpm for at least 3 minutes.
(d) After confirming that the waveform of the heated oxygen sensor (bank 1, 2 sensor 1 (HA1A, HA2A)),
oscillate around 0.5 V during feedback to the ECM, check the waveform of the heated oxygen sensor
(bank 1, 2 sensor 2 (OX1B, OX2B)).