O2 sensor TOYOTA SEQUOIA 2001 Service Repair Manual

± DIAGNOSTICSENGINE
DI±449
643 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
Following values are values when atmo-
spheric is 760 mmHg (100 kPa)±
EVAP key±off monitor runs when all of the
following conditions met:±
Atmospheric pressure525 to 825 mmHg (70 to 110 kPa)
Battery voltage10.5 V±
Vehicle speed±4 km/h (2.5 mph)
Ignition switchOFF
Engine conditionNot running
Time after engine stopped5 hours
FTP sensor malfunction (P0450, P0452,
P0453)Not detected
Purge VSVNot operated by scan tool
Vent valveNot operated by scan tool
Leak detection pumpNot operated by scan tool
Both of the following conditions are met
before IG switch OFFCondition 1 and 2
1. Duration that vehicle is driven5 min.±
2. Purge flowExecuted
ECT4.4 to 35°C (40 to 95°F)
IAT4.4 to 35°C (40 to 95°F)
Example of re±start time±
First time7 hours
Second time9 hours and 30 min.
Key±off monitor sequence1 to 8
1. Atmospheric pressure±
Next sequence is run if following condition
set±
Atmospheric pressure change for 10 sec.±2.25 mmHg (0.3 kPa) for 1 sec.
2. First reference pressure±
Next sequence is run if all of following
conditions setCondition 1, 2 and 3
1. FTP when 4 sec. after reference pres-
sure measurement±±7.5 mmHg (±1 kPa)
2. Reference pressure±36.38 to ±7.93 mmHg (±4.85 to ±1.057 kPa)
3. Reference pressureSaturated
3. Vent valve stuck closed check±
Next sequence is run if following condition
set±
FTP change for 10 sec. after vent valve
ON (closed)2.25 mmHg (0.3 kPa)±
4. Vacuum introduction and leak±

A23458
Air±fuel Ratio Sensor Output:
Active A/F Control
A/F Sensor Output
Fuel Injection VolumeON
OFF
NormalMalfunction 10 Seconds
± DIAGNOSTICSENGINE
DI±451
645 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2A00 A/F Sensor Circuit Slow Response (Bank 1
Sensor 1)
DTC P2A03 A/F Sensor Circuit Slow Response (Bank 2
Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P2195 on page DI±383.
DTC No.DTC Detection ConditionsTrouble Areas
P2A00
P2A03Calculated test value for A/F sensor response rate deteriora-
tion level is less than threshold.
Open or short in A/F sensor (sensor 1) circuit

A/F sensor (sensor 1)

ECM
MONITOR DESCRIPTION
After engine is warmed up, the ECM performs air±fuel ratio feedback control to regulate the air±fuel ratio
at stoichiometric ratio. In addition, this vehicle performs Active A/F Ratio Control for approximately 10 se-
conds after preconditions met in order to measure the A/F sensor response rate. During active air±fuel ratio
control, the ECM forcibly increases and decreases the injection volume for certain amount based on learned
stoichiomentric air ±fuel ratio during usual air±fuel feedback control, and measures the A/F sensor response
rate. The ECM calculates the signal from the A/F sensor while value for A/F sensor response rate deteriora-
tion level.
If the test value for A/F sensor response rate deterioration level is less than threshold, ECM interprets this
as a malfunction, and sets the DTC.
DIDFY±01

Vehicle speed
(40 ±120 km/h)25 ± 75mph)
(g)(h)
Warm up
3 minutes DI±452
± DIAGNOSTICSENGINE
646 Author: Date:
2005 SEQUOIA (RM1146U)
CONFIRMATION DRIVING PATTERN
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the hand±held tester ON.
(d) Clear DTCs.
(e) Select the following menu items: DIAGNOSIS/ENHANCED OBD II/MONITOR INFO/MONITOR RE-
SULT.
(f) Check that RES RATE B1 S1 is INCOMPL.
(g) Start the engine and warm it up.
(h) Drive the vehicle at between 25 mph and 75 mph (40 km/h and 120km/h) for 3 minutes. However, the
vehicle should be driven at constant±speed.
(i) When detection is complete, Response rate of MONITOR RESULT changes.
If the value does not change, perform step (g) once more.
(j) Notes the value of the Monitor Result.
(k) Select the following menu items: DIAGNOSIS/ENHANCED OBD II/DTC INFO/ PENDING CODES.
(l) Check if any DTCs (any pending DTCs) are set.
MONITOR STRATEGY
RltdDTCP2A00A/F sensor (Bank 1) slow responseRelated DTCsP2A03A/F sensor (Bank 2) slow response
Required sensors/componentsA/F sensor
Frequency of operationOnce per driving cycle
Duration10 to 15 sec.
MIL operation2 driving cycles
Sequence of operationNone

± DIAGNOSTICSENGINE
DI±453
647 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
Battery voltage11 V±
ECT75°C (167°F)±
IdleOFF
Engine RPM±4,000 rpm
A/F sensor statusActivated
Fuel cutOFF
Engine load10 to 70%
Estimated catalyst temperature500 to 800°C (932 to 1,472°F)
Shift position2nd±
Catalyst monitorNot executing
Intake air amount2.5 to 12 g/sec
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Response rate deterioration levelLess than 0.2 V
Number of average5 or more
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 OBD ll scan tools.
A/F sensor bank 1 sensor 1
MIDTIDScalingDescription of Test ValueMinimum Test LimitMaximum Test Limit
$01$8EMultiply by 0.0003
(no dimension)Response rate deterioration level for
A/F sensorMalfunction criterionFF
A/F sensor bank 2 sensor 1
MIDTIDScalingDescription of Test ValueMinimum Test LimitMaximum Test Limit
$05$8EMultiply by 0.0003
(no dimension)Response rate deterioration level for
A/F sensorMalfunction criterionFF
WIRING DIAGRAM
Refer to DTC P2195 on page DI±383.

DI±454
± DIAGNOSTICSENGINE
648 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:
Hand±held tester only:
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.
The following instructions describe how to conduct the A/F CONTROL operation using a hand±held tester.
(1) Connect a hand±held 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 (AFS B2S1) and OS2 B1S2
(O2S B2S2)) displayed on the tester.
HINT:

The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection
volume by 25 %.

Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard:
Tester Display
(Sensor)Injection VolumesStatusVoltages
AFS B1S1 (AFS B2S1)
(A/F)+25 %RichLess than 3.0
AFS B1S1 (AFS B2S1)
(A/F)±12.5 %LeanMore than 3.35
O2S B1S2 (O2S B2S2)
(HO2)+25 %RichMore than 0.55
O2S B1S2 (O2S B2S2)
(HO2)±12.5 %LeanLess than 0.4

+25 %
±12.5 %
More than 3.35 V
Less than 3.0 V
1
A/F Sensor (Sensor 1)
Output Voltage
Injection volume
Output voltage
HO2 Sensor (Sensor 2)
Output VoltageMain Suspected
Trouble Areas
OK
+25 %
±12.5 %
More than 3.35 V
Less than 3.0V
Injection volume
Output voltage
+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
Injection volume
Output voltage
A/F sensor+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
Injection volume
Output voltage
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NG OK
OK
OK
Almost
no reaction
'
Almost
no reaction Almost
no reaction
Almost
no reaction
Case
2
3
4
A/F sensor circuit A/F sensor heater
HO2 sensor
HO2 sensor circuit HO2 sensor heater
(Air±fuel ratio extremely
lean or rich)Injector
Gas leakage from
exhaust system Fuel pressure
± DIAGNOSTICSENGINE
DI±455
649 Author: Date:
2005 SEQUOIA (RM1146U)
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.

Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs
of both the A/F and HO2 sensors.

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, and press the YES but-
ton and then the ENTER button followed by the F4 button.
HINT:

DTC P2A00 may be also set, when the air±fuel ratio is stuck rich or lean.

A low A/F sensor voltage could be caused by a rich air±fuel mixture. Check for conditions that would
cause the engine to run rich.

A high A/F sensor voltage could be caused by a lean air±fuel mixture. Check for conditions that would
cause the engine to run lean.

Read freeze frame data using a hand±held tester or OBD II scan tool. Freeze frame data record 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.

B17396
HT +B
AF± AF+ Sensor 1A/F Sensor Component Side:
Front View
DI±456
± DIAGNOSTICSENGINE
650 Author: Date:
2005 SEQUOIA (RM1146U)
1 Check any other DTCs output (in addition to DTC P2A00 or P2A03).
PREPARATION:
(a) Connect a hand±held tester to the DLC3.
(b) Turn the ignition switch to ON and turn the tester ON.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
CHECK:
(a) Read DTCs.
Result:
Display (DTC Output)Proceed To
P2A00 and/or P2A03A
P2A00 and/or P2A03 and other DTCsB
HINT:
If any DTCs other than P2A00 and/or P2A03 are output, troubleshoot those DTCs first.
B Go to DTC chart (See page DI±58).
A
2 Check resistance of air±fuel ratio (A/F) sensor heater.
PREPARATION:
Disconnect the air±fuel ratio (A/F) sensor connector.
CHECK:
Measure resistance between the terminals of the A/F sensor
connector.
OK:
Standard:
Tester ConnectionSpecified Condition
HT (1) ± +B (2)Between 1.8 W and 3.4 W at 20C (68F)
HT (1) ± AF± (4)10 kW or higher
NG Replace air±fuel ratio (A/F) sensor.
OK

A23659
Wire Harness Side:
HT
A38
Sensor 1A/F Sensor Connector
AF+
Front ViewAF±
+B A39
B17415A55007
E7ECM Connector
HA1A
A1A+
A1A±
A2A+
A2A±HA2A
A23512
Reference (Bank 1 Sensor 1 System Drawing):
A/F Sensor A/F Relay
Heater
Sensor
A1A+ HA1A
Duty
Control ECM
From
Battery
A/F Heater
Fuse
A1A±
To EFI Relay
± DIAGNOSTICSENGINE
DI±457
651 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check for open and short in harness and connector between ECM and A/F sen-
sor.
PREPARATION:
(a) Disconnect the A38 or A39 A/F sensor connector.
(b) Turn the ignition switch to ON.
CHECK:
(a) Measure the voltage between the +B terminal of the A/F
sensor connector and body ground.
OK:
Standard:
Tester ConnectionsSpecified Conditions
+B (2) ± Body groundBetween 9 V and 14 V
PREPARATION:
(a) Turn the ignition switch to OFF.
(b) Disconnect the E7 ECM connector.
CHECK:
(a) Check the resistance.
OK:
Standard (Check for open):
Tester ConnectionsSpecified Conditions
HT (A38±1) ± HA1A (E7±2)
HT (A39±1) ± HA2A (E7±1)Below 1 W
AF+ (A38±3) ± A1A+ (E7±22)
AF+ (A39±3) ± A2A+ (E7±23)Below 1 W
AF± (A38±4) ± A1A± (E7±30)
AF± (A39±4) ± A2A± (E7±31)Below 1 W
Standard (Check for short):
Tester ConnectionsSpecified Conditions
HT (A38±1) or HA1A (E7±2) ± Body ground
HT (A39±1) or HA2A (E7±1) ± Body ground10 kW or higher
AF+ (A38±3) or A1A+ (E7±22) ± Body ground
AF+ (A39±3) or A2A+ (E7±23) ± Body ground10 kW or higher
AF± (A38±4) or A1A± (E7±30) ± Body ground
AF± (A39±4) or A2A± (E7±31) ± Body ground10 kW or higher

DI±458
± DIAGNOSTICSENGINE
652 Author: Date:
2005 SEQUOIA (RM1146U)
NG Replace or replace harness or connector.
OK
4 Perform confirmation driving pattern.
NEXT
5 Check whether DTC output recurs (DTC P2A00 or P2A03)
CHECK:
(a) On the hand±held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / PENDING CODES.
(b) Read DTCs.
RESULT:
Display (DTC Output)Proceed To
P2A00 or P2A03A
No outputB
B Check for intermittent problems
(See page DI±11).
A
6 Replace air fuel ratio sensor.
NEXT
7 Perform confirmation driving pattern.
NEXT

0.02 inch orifice clogged
Pressure sensor low outputP043E
P043FP0441 P0451 P0452 P0453 P0455 P0456 P2419P2401
P2402
0.02 inch orifice high±flow
Pressure sensor stuck
Pressure sensor noise
Gross leak
Small leak
Vacuum pump stuck OFF
Vacuum pump stuck ON
Vent valve stuck closed
Vent valve stuck open (vent) Purge VSV stuck open
Purge VSV stuck closed
Pressure sensor high output
DTCs
Malfunctioning AreasP2420 P0450
DI±460
± DIAGNOSTICSENGINE
654 Author: Date:
2005 SEQUOIA (RM1146U)
EVAP (Evaporative Emission) Inspection Procedure
DTCS RELATING TO EVAP SYSTEM
DTCsMonitoring ItemsSee Page
P043E0.02 inch orifice clogged (built into pump module)DI±445
P043F0.02 inch orifice high±flow (built into pump module)DI±445
P0441

Purge VSV (Vacuum Switching Valve) stuck closed

Purge VSV stuck open

Purge flow
DI±257
P0450Pressure sensor (built into pump module) voltage abnormal fluctuationDI±264
P0451
Pressure sensor (built into pump module) noising

Pressure sensor stuck (built into pump module)DI±264
P0452Pressure sensor (built into pump module) voltage lowDI±264
P0453Pressure sensor (built into pump module) voltage highDI±264
P0455EVAP gross leakDI±273
P0456EVAP small leakDI±273
P2401Vacuum pump stuck OFF (built into pump module)DI±410
P2402Vacuum pump stuck ON (built into pump module)DI±410
P2419Vent valve stuck closed (built into pump module)DI±416
P2420Vent valve stuck open (vent) (built into pump module)DI±416
P2610Soak timer (built into ECM)DI±442
If any EVAP system DTCs are set, the malfunctioning area can be determined using the table below.
NOTICE:
If the 0.02 inch reference pressure difference between the first and second checks is greater than
the specification, the DTCs corresponding to the reference pressure (P043E, P043F, P0441, P0455,
P0456, P2401, P2420) will be all stored.
DIDFZ±01